Wrong shell variable used when changing directory

Fix panic when restarting non-running task

This PR fixes an issue that is hit when running templates with restart
mode in which the client could panic when the handle is not running.

Fixes https://github.com/hashicorp/nomad/issues/2479

Updated logo in README.md

The logo file has been moved with [d9640776](https://github.com/hashicorp/nomad/commit/d96407769a4a33901b5de66b7053e08574428698) by @sethvargo. Hence the logo reference in the README.md is broken. This PR fixes that.

Fix diff alignment and remove no change DC

Old Output:
```
+/- Job: "example"
    Datacenters {
  Datacenters: "dc1"
}
+/- Task Group: "cache" (1 create/destroy update)
  +/- RestartPolicy {
    +/- Attempts: "10" => "9"
        Delay:    "25000000000"
        Interval: "300000000000"
        Mode:     "delay"
  }
  +/- EphemeralDisk {
        Migrate: "false"
    +/- SizeMB:  "300" => "301"
        Sticky:  "false"
  }
  +/- Task: "redis" (forces create/destroy update)
    +   Meta[key]: "value"
    +/- Config {
          image:           "redis:3.2"
      +/- port_map[0][db]: "6379" => "6380"
    }
    +/- Resources {
          CPU:      "500"
          DiskMB:   "0"
          IOPS:     "0"
      +/- MemoryMB: "256" => "257"
    }
    +/- Service {
          Name:      "global-redis-check"
          PortLabel: "db"
      +/- Check {
            Command:       ""
            InitialStatus: ""
            Interval:      "10000000000"
            Name:          "alive"
            Path:          ""
            PortLabel:     ""
            Protocol:      ""
        +/- Timeout:       "2000000000" => "3000000000"
            Type:          "tcp"
      }
    }
```

New Output:
```
+/- Job: "example"
+/- Task Group: "cache" (1 create/destroy update)
  +/- RestartPolicy {
    +/- Attempts: "10" => "9"
        Delay:    "25000000000"
        Interval: "300000000000"
        Mode:     "delay"
      }
  +/- EphemeralDisk {
        Migrate: "false"
    +/- SizeMB:  "300" => "301"
        Sticky:  "false"
      }
  +/- Task: "redis" (forces create/destroy update)
    +   Meta[key]: "value"
    +/- Config {
          image:           "redis:3.2"
      +/- port_map[0][db]: "6379" => "6380"
        }
    +/- Resources {
          CPU:      "500"
          DiskMB:   "0"
          IOPS:     "0"
      +/- MemoryMB: "256" => "257"
        }
    +/- Service {
          Name:      "global-redis-check"
          PortLabel: "db"
      +/- Check {
            Command:       ""
            InitialStatus: ""
            Interval:      "10000000000"
            Name:          "alive"
            Path:          ""
            PortLabel:     ""
            Protocol:      ""
        +/- Timeout:       "2000000000" => "3000000000"
            Type:          "tcp"
          }
        }
```

Old Output:

```
+/- Job: "example"
    Datacenters {
  Datacenters: "dc1"
}
+/- Task Group: "cache" (1 create/destroy update)
  +/- RestartPolicy {
    +/- Attempts: "10" => "9"
        Delay:    "25000000000"
        Interval: "300000000000"
        Mode:     "delay"
  }
  +/- EphemeralDisk {
        Migrate: "false"
    +/- SizeMB:  "300" => "301"
        Sticky:  "false"
  }
  +/- Task: "redis" (forces create/destroy update)
    +   Meta[key]: "value"
    +/- Config {
          image:           "redis:3.2"
      +/- port_map[0][db]: "6379" => "6380"
    }
    +/- Resources {
          CPU:      "500"
          DiskMB:   "0"
          IOPS:     "0"
      +/- MemoryMB: "256" => "257"
    }
    +/- Service {
          Name:      "global-redis-check"
          PortLabel: "db"
      +/- Check {
            Command:       ""
            InitialStatus: ""
            Interval:      "10000000000"
            Name:          "alive"
            Path:          ""
            PortLabel:     ""
            Protocol:      ""
        +/- Timeout:       "2000000000" => "3000000000"
            Type:          "tcp"
      }
    }
```

New Output:

```
+/- Job: "example"
+/- Task Group: "cache" (1 create/destroy update)
  +/- RestartPolicy {
    +/- Attempts: "10" => "9"
        Delay:    "25000000000"
        Interval: "300000000000"
        Mode:     "delay"
      }
  +/- EphemeralDisk {
        Migrate: "false"
    +/- SizeMB:  "300" => "301"
        Sticky:  "false"
      }
  +/- Task: "redis" (forces create/destroy update)
    +   Meta[key]: "value"
    +/- Config {
          image:           "redis:3.2"
      +/- port_map[0][db]: "6379" => "6380"
        }
    +/- Resources {
          CPU:      "500"
          DiskMB:   "0"
          IOPS:     "0"
      +/- MemoryMB: "256" => "257"
        }
    +/- Service {
          Name:      "global-redis-check"
          PortLabel: "db"
      +/- Check {
            Command:       ""
            InitialStatus: ""
            Interval:      "10000000000"
            Name:          "alive"
            Path:          ""
            PortLabel:     ""
            Protocol:      ""
        +/- Timeout:       "2000000000" => "3000000000"
            Type:          "tcp"
          }
        }
```

Mention 0.5.5 tool incompat with 0.5.4 agents

Update index.html.md

grammar

ensuring bin directory exists before copying

Mention #2361 in upgrade notes.

build: Add Vault as an external test dependency

deps: Update github.com/shirou/gopsutil/...

Fix test deadlock due to alloc runner not running

Don't actualy call AllocRunner.Run() because that executes so much
unneeded code for this test. Manually close the waitCh to simulate Run()
exiting.

This adds support for Illumos for memory and host information, which
allows the fingerprinting tests to pass. It also contains fixes for
FreeBSD.

Broken things fixed