Remove duplicate call to log handling code. This duplicate call added another
stderr handler to the logger which caused each message to be printed twice to
stderr.

Bugs closed: AURORA-793

Reviewed at https://reviews.apache.org/r/27650/
Mark inotify disk collector test as flaky.

Bugs closed: AURORA-916

Reviewed at https://reviews.apache.org/r/27630/
Replace twitter.commons.io.FileUtils dependency w/ guava's Files

Reviewed at https://reviews.apache.org/r/27545/
Remove SchedulerActive, replace with explicit services.

This is the first part of a larger change that will allow us to
make pubsub events async as it makes the dependency on subscribers
processing a SchedulerActive event explicit.

Testing Done:
./gradlew -Pq build
test_end_to_end.sh

Bugs closed: AURORA-920

Reviewed at https://reviews.apache.org/r/27716/
Fixing the log replay for the job update history pruner.

Bugs closed: AURORA-912

Reviewed at https://reviews.apache.org/r/27598/
Fixing beta-update OK status messaging.

Bugs closed: AURORA-784

Reviewed at https://reviews.apache.org/r/27712/
Simplify management of the driver lifecycle using AbstractidleService.

Bugs closed: AURORA-920

Reviewed at https://reviews.apache.org/r/27746/
Use async eventbus

This change uses AsyncEventBus in production code. Some test code
still expects eventSink.post() to block. I plan to address in a
follow-up review.

Testing Done:
./gradlew -Pq build

Bugs closed: AURORA-920

Reviewed at https://reviews.apache.org/r/27762/