Patch version bumps for bouncy castle, minikdc, snappy, slf4j, scalatest and powermock. Notable fixes:
* Snappy: fixes a resource leak
* Bouncy castle: security fixes
Also update Gradle to 2.11 (where the notable change is improved IDE integration) and the grgit build dependency.
Author: Ismael Juma <ismael@juma.me.uk>
Reviewers: Grant Henke <granthenke@gmail.com>, Ewen Cheslack-Postava <ewen@confluent.io>
Closes#903 from ijuma/kafka-3227-conservative-update-of-kafka-deps