Increase timeout for PyPI HTTP fetches.

This patch increases the timeout for PyPI HTTP fetches. This was
recomended by John Sirois to reduce the flakeyness of Python tests
on Apache Jenkins.

Testing Done:
./build-support/jenkins/build.sh

Reviewed at https://reviews.apache.org/r/26324/
Improve handling of unknown errors in the aurora client.

Instead of dumping the stack on the user's terminal, or
absorbing the error and generating a brief error
message, the client now writes detailed information about
the error is written into an error log file, and the
user is given a clean error message referring them to that
file for details.

Bugs closed: aurora-779

Reviewed at https://reviews.apache.org/r/26328/
Reject new GC tasks when shutting down

Testing Done:
./pants src/test/python/apache/aurora/executor:gc_executor

Bugs closed: AURORA-807

Reviewed at https://reviews.apache.org/r/26432/
Move the error-log seed file to a user specified directory.

Instead of dumping error traces into the users current directory,
dump them into a user specified directory, with a benign default.

Bugs closed: aurora-779

Reviewed at https://reviews.apache.org/r/26448/
Fix error in incorrect deprecation warning on v1 "ssh" command.

The error message incorrectly displayed a list-value for the
"--tunnels" parameter, when in fact it should expand the list
into multiple instances of "--tunnels".

Testing Done:
New unit test.

Bugs closed: aurora-804

Reviewed at https://reviews.apache.org/r/26445/
Don't kill GC Executor after period of inactivity

The GC executor is configured to exit after 15 minutes of
inactivity. This leads to a race where the mesos slave gets a
launchTask message for a GC executor just as the executor has exited,
causing TASK_LOST noise. This also increases the risk that a slave
will lose its GC executor due to the scheduler not being able to find
a slot for it (since GC executors will have a higher churn rate).

Cluster operators will still be able to deploy new versions of the
GC executor as the 24-hour max lifetime limit is still in place. This
patch only removes the inactivity limit.

Testing Done:
./pants src/test/python/apache/aurora/executor:gc_executor

Bugs closed: AURORA-788

Reviewed at https://reviews.apache.org/r/26300/
Drop syncrhonized from JobUpdateEventSubscriber

This fixes a startup deadlock.

Testing Done:
./gradlew -Pq build

Manually verified that all delegated calls to the JobUpdateController
are already protected by the storage write-lock.

Rather than add a potentially-flaky regression test (like
the one added in https://reviews.apache.org/r/25556/)
I'd prefer to prioritize adding runtime deadlock detection
(https://issues.apache.org/jira/browse/AURORA-800).

Bugs closed: AURORA-801

Reviewed at https://reviews.apache.org/r/26422/
Fixing python style violations.

Reviewed at https://reviews.apache.org/r/26428/
Remove cron_policy related code.
Remove daemon bit.
Remove Twitter Specific links.
Remove health_check_interval_secs property.
Remove recipes.
Remove packer references.
Fix checkstyle issues.
Fix Import Order.