Setting the max thread limit on AsyncEventBus.

Bugs closed: AURORA-926

Reviewed at https://reviews.apache.org/r/27947/
Reset CHANGELOG and .auroraversion in prep for 0.6.0-RC2.

Reviewed at https://reviews.apache.org/r/28005/
Add friendly error message to the client when lock is held.

Bugs closed: AURORA-885

Reviewed at https://reviews.apache.org/r/27848/
Updating CHANGELOG for 0.6.0 release.
Incrementing snapshot version to 0.6.1-SNAPSHOT.
Splitting cron and non-cron job creation in client v2.

Bugs closed: AURORA-917

Reviewed at https://reviews.apache.org/r/27747/
Adding resource consumption calculation for cron jobs.

Bugs closed: AURORA-825

Reviewed at https://reviews.apache.org/r/27601/
Require StateManager callers to open their own transactions.

Reviewed at https://reviews.apache.org/r/26899/
Fix task_util dependency and add it to all target.

Reviewed at https://reviews.apache.org/r/28048/
Show update page URL in the output for beta-update start.

Bugs closed: AURORA-766

Reviewed at https://reviews.apache.org/r/28019/
Move zookeeper connection off the main thread to prevent client deadlocks.

Reviewed at https://reviews.apache.org/r/27698/
Remove dependency on commons-lang.

Testing Done:
./gradlew clean build -Pq

Reviewed at https://reviews.apache.org/r/28021/
Drop argparse dependency; it's part of python 2.7

Testing Done:
./pants build src/test/python:all
bash src/test/sh/org/apache/aurora/e2e/test_end_to_end_v2.sh

Bugs closed: AURORA-891

Reviewed at https://reviews.apache.org/r/28140/
AURORA-933 - python missing license headers

Adds missing license headers to .py files

Bugs closed: AURORA-933

Reviewed at https://reviews.apache.org/r/28170/
Add more test coverage to SchedulerThriftInterface.

Bugs closed: AURORA-937

Reviewed at https://reviews.apache.org/r/28026/
Simplify Preemptor code, encapsulate parameters used there and in SchedulingFilter.

Reviewed at https://reviews.apache.org/r/28103/
Ensure all verbs return an exit code.

Bugs closed: AURORA-923

Reviewed at https://reviews.apache.org/r/27852/
Fix test_version to use explicit injection points.

Testing Done:
./pants src/test/python:all
./pants src/main/python/apache/aurora/client/bin:aurora_client
dist/aurora_client.pex version

Bugs closed: AURORA-938

Reviewed at https://reviews.apache.org/r/28250/
Fixing flaky LockManager test.

Bugs closed: AURORA-798

Reviewed at https://reviews.apache.org/r/28066/
Adding instrumentation into the scheduling pipeline.

Bugs closed: AURORA-914

Reviewed at https://reviews.apache.org/r/27705/