Implement client command logging with a unique token.

Adding a centralized logger interface for clientv2.

For the aurora analytics work, we need some hooks for logging. We'd
like all client logging to go through a common interface, and for
client logs that might be sent to the centralized logging service to
be tagged with identifiers and userids.

This change implements a simple minimal logging function that's used
by clientv2 logging calls, and which attaches a universally unique
client identifier to each log message.

Bugs closed: aurora-276

Reviewed at https://reviews.apache.org/r/19396/
Add batching to the kill and killall commands.

Bugs closed: aurora-283

Reviewed at https://reviews.apache.org/r/19466/
Allow override of default RB server in shipits tool.

Reviewed at https://reviews.apache.org/r/19519/
Add maintenance commands into aurora_admin

Bugs closed: AURORA-288

Reviewed at https://reviews.apache.org/r/19694/
Now consuming nonProd consumption from the new getQuota API

Updated the client to consume the new getQuota API which contains
nonProdConsumption(resources consumed by non-prod tasks) information also.

Currently, the mocked calls can't detect renamed and missing thrift structs. Added tests
to look for expected fields in GetQuotaResult and  ResourceAggregate structs.
Refactored tests in test_quota to remove duplicated code and added a missing test.

Testing Done:
./pants src/test/python:all -vxs

Bugs closed: AURORA-246

Reviewed at https://reviews.apache.org/r/19509/
Filtering out non-prod tasks for domain sla calculations.

Bugs closed: AURORA-287

Reviewed at https://reviews.apache.org/r/19550/
AURORA-278: Review Incubator release check list

License header cleanup due to recently added files missind headers.

Also updates LICENSE and NOTICE to correctly address bundled dependencies.

Bugs closed: AURORA-278

Reviewed at https://reviews.apache.org/r/19727/
AURORA-132: crontab(5) entry parser.

Testing Done:
./gradlew build

Bugs closed: AURORA-132

Reviewed at https://reviews.apache.org/r/19709/
CronScheduler based on Quartz.
Kill No-op cron scheduler.
Merge AbstractCronIT with QuartzCronIT