Document new status command

This PR documents the new status and job status command.

Fix TLS support in api pkg / cli

- No need to for a pointer to a pointer
- Properly set and use QueryOptions.Region

If MaxParallel == 0 default limit to count

All context should use string context "all"

Squelch logspam when unable to get disk usage stats

Automatically install autocomplete for Nomad getting started guide

Describe the all parameter when listing job allocs

To reproduce logspam:

```
$ docker plugin install --grant-all-permissions vieux/sshfs
$ nomad agent -dev
...
2017/08/25 17:09:03.282868 [WARN] client: error fetching host disk usage stats for /var/lib/docker/plugins/a8b4a69b07e5180f828d19e1e9e102ccc0e26f9c9939eaef85357260c30b20a7/rootfs/mnt/volumes: permission denied
... repeats every collection period ...
```

Fixes #3013

It's a little weird that Client now has a method for returning a
NewClient, but it's a convenient way to dedupe the logic to
connect-directly-to-a-node which is nontrivial and had sutble
differences between locations.

This PR moves creating the API client into the returned predict
function. The creation of the client causes a lookup of all the system
certificates and doing that for each command on mac was extremely slow.

@chelseakomlo heads up on this change

Get status of deployment via status cli command

Status autocomplete

Add HTTP documentation for search api

fixups from code review

defaults to listing jobs if no id is provided