Command hooks: stage 2.

The second half of command hooks:
- Dynamically registered hook exceptions are provided, by fetching a hooks skip rules file
  from a URL.
- Hooks are loaded and activated by the noun/verb framework.
- Hook selection and dispatch has been substantially updated.

Also did some long overdue cleanup of string quoting consistency.

Bugs closed: aurora-270

Reviewed at https://reviews.apache.org/r/20928/
Add batch options to kill and killall. (This brings the kill commands in client v1
into parity with client v2. At the moment, in order to avoid disrupting current users,
v1 still defaults to non-batched operation.)

Bugs closed: aurora-356

Reviewed at https://reviews.apache.org/r/20723/
Avoid sending tasks in SANDBOX_DELETED state to the GC executor.

Bugs closed: AURORA-395

Reviewed at https://reviews.apache.org/r/21142/
AURORA-388 - Update changelog to only pickup fixed issues

Updates the changelog jql to only pick up fixed and done issues.

Testing Done:
Removed CHANGELOG file and switched .auroraversion to 0.5.0 and re-ran script, came back with 160 issues vs the 183 currently listed.

Bugs closed: AURORA-388

Reviewed at https://reviews.apache.org/r/21111/
Add a clientv2 version of the e2e test.

Bugs closed: aurora-266

Reviewed at https://reviews.apache.org/r/19788/
Moving kill wait to the client (Part 2: server changes)

Bugs closed: AURORA-370

Reviewed at https://reviews.apache.org/r/20959/
Adding min_instance_count threshold to improve safe domain results.

Bugs closed: AURORA-305

Reviewed at https://reviews.apache.org/r/20986/
Fix broken test build.

Bugs closed: aurora-397

Reviewed at https://reviews.apache.org/r/21188/
Fixed wrapped sandbox link.

Testing Done:
Tested on local laptop.

Bugs closed: AURORA-396

Reviewed at https://reviews.apache.org/r/21145/
Added tooltip to a disabled task sandbox link.

Testing Done:
tested on laptop.

Bugs closed: AURORA-402

Reviewed at https://reviews.apache.org/r/21242/
Always show resource consumption table on Job page.

Testing Done:
Tested on local laptop. Screenshots attached.

Bugs closed: AURORA-386

Reviewed at https://reviews.apache.org/r/21144/
Add a strict mode for commands that specify instances.

If strict mode is on, and users specify an invalid shard range (a range that's larger that the actual
number of shards), then generate an error.

Bugs closed: aurora-401

Reviewed at https://reviews.apache.org/r/21232/
Bugfix: make "restart" command generate a correct error message in some cases.

Bugs closed: aurora-400

Reviewed at https://reviews.apache.org/r/21223/
Add return code to task/process pages

Reviewed at https://reviews.apache.org/r/20394/
Add python import order wrapper/commit hook

Adds build-support/isort wrapper for isort.

Adds build-support/isort-run to run import sort, build-support/isort-check
to run import order check.

Adds build-support/hooks which contains hooks that people can place into
their .git/hooks directory, currently just a pre-commit hook that checks
import sort order (which can be overridden with an environment variable.)

The ordering it produces is different than the one we currently have but
closer to straight PEP8.  If it runs, it's about a 500 line diff which I can
send later.

Testing Done:
Ran the isort and ran tests, everything worked.

Bugs closed: AURORA-149

Reviewed at https://reviews.apache.org/r/21136/
Apply build-support/isort-run

This applies build-support/isort-run.  This is an automatically generated
diff without any editing on my part.  I sent this review with the git hook
enabled and it passed:

mba=aurora=; git commit -a -m "Apply build-support/isort-run"
Performing Python import order check.
SUCCESS
[wickman/apply_isort 17a14e6] Apply build-support/isort-run
 169 files changed, 751 insertions(+), 1029 deletions(-)

Instructions for integrating it into your workflow are in the .isort.cfg at
the root of the repository.

Reviewed at https://reviews.apache.org/r/21333/
Switching to untracked StatsProvider.

Bugs closed: AURORA-406

Reviewed at https://reviews.apache.org/r/21350/
Fix regression causing scheduling rate limiter to not be honored.

Also added findbugs to the build.

Bugs closed: AURORA-416

Reviewed at https://reviews.apache.org/r/21352/
Bugfix: restart doesn't notify user about invalid max_total_failures option.

Bugs closed: aurora-399

Reviewed at https://reviews.apache.org/r/21205/
Make the "task run" command accept an instances spec.

Also, add a subclass of DistributedCommandRunner that takes an
instance list, and runs a command only on the specific task instances
in that list.

Bugs closed: aurora-198

Reviewed at https://reviews.apache.org/r/21170/