Revert "Run python style checks in jenkins."

Reviewed at https://reviews.apache.org/r/26093/
Add updater support for disabling rollback and batched update settings.

Bugs closed: AURORA-744, AURORA-747

Reviewed at https://reviews.apache.org/r/26106/
Fix instance summary visualisation.

Bugs closed: AURORA-755

Reviewed at https://reviews.apache.org/r/26095/
Upgrade to gradle 2.1

Reviewed at https://reviews.apache.org/r/26113/
Prevent initial ZK timeouts from killing the executor.

In addition, prevent uncaught exceptions from killing the executor.
Kevin's feedback.
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Kevin's Feedback.
Brian's Feedback.
Split client creation and serverset generation.
WIP
WIP WIP WIP