Include the _ prefix separator in both regexes

And include all prefix types in the test data

UI: Allocation lifecycle

logmon: remove syslog server deadcode

Grab bag of (primarily race) test fixes

exec: allow drivers to handle stream termination

client: synchronize access to `ar.alloc`

No longer used

nomad: fix race in BlockedEvals

`allocRunner.alloc` is protected by `allocRunner.allocLock`, so let's
use `allocRunner.Alloc()` helper function to access it.

Accidentally accessed outer `err` variable inside a goroutine

Close is invoked in a different goroutine from test

naive implementation should focus on ascii characters only

Without this change, alloc_endpoint cancel the context passed to handler
when we detect EOF.  This races driver in setting exit code; and we run
into a case where the exec process terminates cleanly yet we attempt to
mark it as failed with context error.

Here, we rely on the driver to handle errors returned from Stream and
without racing to set an error.

Remove unused syslog server related code that got replaced by the docker
logger in Nomad 0.9

Previous commit could introduce a deadlock if the capacityChangeCh was
full and the receiving side exited before freeing a slot for the sending
side could send. Flush would then block forever waiting to acquire the
lock just to throw the pending update away.

The race is around getting/setting the chan field, not chan operations,
so only lock around getting the chan field.

I assume the mutex was being released before sending on capacityChangeCh
to avoid blocking in the critical section, but:

1. This is race.
2. capacityChangeCh has a *huge* buffer (8096). If it's full things
   already seem Very Bad, and a little backpressure seems appropriate.

Block plan application until state store has caught up to raft

UI: Replace the adapter cancellation methods with a cancellation token system

api: allow configuring http client

`*Config.ConfigureTLS()` is invoked internally by `NewClient` and API
consumers should not invoke directly.

Now that http client is created in `api.NewClient`,
`*Config.ConfigureTLS` makes no sense.  API consumers that call it
explicitly can remove the invocation and preserve the behavior.