Don't persist allocs of destroyed alloc runners

Protect against a race where destroying and persist state goroutines
race.

The downside is that the database io operation will run while holding
the lock and may run indefinitely.  The risk of lock being long held is
slow destruction, but slow io has bigger problems.

scheduler: Implicit constraint on readonly hostvol

logmon: revert workaround for Windows go1.11 bug

ci: use circleci/golang images directly

This fixes a bug where allocs that have been GCed get re-run again after client
is restarted.  A heavily-used client may launch thousands of allocs on startup
and get killed.

The bug is that an alloc runner that gets destroyed due to GC remains in
client alloc runner set.  Periodically, they get persisted until alloc is
gced by server.  During that  time, the client db will contain the alloc
but not its individual tasks status nor completed state.  On client restart,
client assumes that alloc is pending state and re-runs it.

Here, we fix it by ensuring that destroyed alloc runners don't persist any alloc
to the state DB.

This is a short-term fix, as we should consider revamping client state
management.  Storing alloc and task information in non-transaction non-atomic
concurrently while alloc runner is running and potentially changing state is a
recipe for bugs.

Fixes https://github.com/hashicorp/nomad/issues/5984
Related to https://github.com/hashicorp/nomad/pull/5890

Revert e0126123 now that we are running
with Golang 1.12, and https://github.com/golang/go/issues/29119 is no
longer relevant.

initialize device manager stats interval

We currently use an container image for `test-devices` job only; while
all other jobs use machine executor.

This allows us to switch golang and protoc verions easily without
manually managing Docker images (which requires building them manually
on a dev machines, etc).  All that while, we install dependencies on
every build in all other jobs..

`test-devices` now is one of the fastest jobs and isn't a constraint or
a bottleneck, so increasing its overhead by few seconds doesn't hurt the
overall developer iteration.

If we split tests effectively later, we can revisit.

Fixes `test-devices` job

clientConfig.Copy() to copy template config too

Update ugorji/go to latest

exec driver setuid go-getter update

Fixes a bug where we cpu is pigged at 100% due to collecting devices
statistics.  The passed stats interval was ignored, and the default zero
value causes a very tight loop of stats collection.

FWIW, in my testing, it took 2.5-3ms to collect nvidia GPU stats, on a
`g2.2xlarge` ec2 instance.

The stats interval defaults to 1 second and is user configurable.  I
believe this is too frequent as a default, and I may advocate for
reducing it to a value closer to 5s or 10s, but keeping it as is for
now.

Fixes https://github.com/hashicorp/nomad/issues/6057 .

Update golang to 1.12.9

The dev mode flag for connect was binding to the default interface's
IP, but this makes for a bad user experience for the CLI which will
default to 127.0.0.1. If we bind to 0.0.0.0 instead the CLI will work
without further configuration by the user.

* adds meta object to service in job spec, sends it to consul

* adds tests for service meta

* fix tests

* adds docs

* better hashing for service meta, use helper for copying meta when registering service

* tried to be DRY, but looks like it would be more work to use the
helper function

This removes the in-repository Netlify configuration. There are now two
sites backed by the repository, so we must use the web UI to
control the build settings, as having the configuration in-repository
overrides the web UI settings.

The build settings for the two sites are below, as of this commit. See
the extra step in nomad-ui site’s build step that copies the _redirects
file to the correct destination so things are properly forwarded when
you visit the deployment.

nomad-ui:

base directory: ui
build command: ember build && mkdir -p ui-dist/ui && mv dist/* ui-dist/ui/ && cp ../.netlify/ui-redirects ui-dist/_redirects
publish directory: ui/ui-dist

nomad-website:

base directory: website
build command: bundle exec middleman build
publish directory: website/build

connect: task hook for bootstrapping envoy sidecar

Fixes #6041

Unlike all other Consul operations, boostrapping requires Consul be
available. This PR tries Consul 3 times with a backoff to account for
the group services being asynchronously registered with Consul.

ci: Use more recent base machine executor image for test-rkt

This fixes a frequent failure in `test-rkt` jobs where dpkg installation
fails.

The image used currently, circleci/classic:201808-01, has unattended
upgrades enabled accidentally, which runs on every build.  This means
that tools get modified unexpectedly during builds, and apt-get commands
may fail as the unattended upgrade is holding package database lock.

This updates `test-rkt` job only because the new image breaks
`test-docker` job (e.g. https://circleci.com/gh/hashicorp/nomad/2641 ),
and I punted on investigating test-docker for another day.

remove hidden field from host volumes

We're not shipping support for "hidden" volumes in 0.10 any more, I'll
convert this to an issue+mini RFC for future enhancement.

api: Fix definition of HostVolumeInfo

clientconfig: Fix parsing multiple host volumes