The previous integration test was broken during the client refactor, and
it seems to be some sort of race with state updating.

I'm going to try and construct a replacement test as part of work on
performance, but for now, the underlying behaviour is still being
tested.

Fix various bugs with task events

Fixes the following:
* Emitting events when the task fails to start
* Don't double emit events on task shutdown (nomad stop)
* Don't emit a OOM kill metric unless actually OOM'd

server/vault: Lock Vault expiration tracking

tests: fix rkt tests

The rkt command itself needs an environment with PATH set to find iptables.

Add guards around subtracting summary count

Also update the new recommended `nomad job` subcommands

* Add Nomad RA

* Add deployment guide and nav

* Deployment Guide update

* Minor typo fixes

* Update diagrams

* Fixes for review

* Link fixes and typo fix

* Edits following review

- Update image text from "zone" to "datacenter" to match Nomad terminology
- Clean up text based on Preetha's feedback

* Text updates

Based on feedback from Rob

* Update diagrams

* fixing spelling

* Add suggestions from Preetha and Omar

WaitForResult expects body to fail and retries few times before giving
up.  Assertions inside the testfn body causes it to terminate abruptly
without retrying.

`currentExpiration` field is accessed in multiple goroutines: Stats and
renewal, so needs locking.

I don't anticipate high contention, so simple mutex suffices.

When `t.Parallel()` is used inside a `t.Run()` sub-set, the closure
doesn't behave as expected, and some cases effectively get skipped.
More details can be found in
https://gist.github.com/posener/92a55c4cd441fc5e5e85f27bca008721

Third Party Driver Plugins Support

no need to double the work

libcontainer already manages `/dev`, overriding task_dir - so let's use it for `/proc` as well and remove deadcode.

this allows us to drop a cyclical import, but is subobptimal as it
requires BaseDriver tests to move. This falls firmly into the realm of
being a hack. Alternatives welcome.

This removes a cyclical dependency when importing client/structs from
dependencies of the plugin_loader, specifically, drivers. Due to
client/config also depending on the plugin_loader.

It also better reflects the ownership of fingerprint structs, as they
are fairly internal to the fingerprint manager.

Batch update for the PRs I recently merged.

Refactor and repackage client/driver

Use user provided image name to launch container

Support bind and tmpfs docker mounts

Co-Authored-By: notnoop <mahmood@notnoop.com>

With the introduction of driver plugins, we're temporarily relying on
_run time validation_ of driver configurations, rather than submission
time.