Removed unnecessary undocumented methods in Gerrit trigger to fix JENKINS-24787
Replaced short names in GerritEventContext by DSL methods
converted all tests to Spock
removed trailing whitespace
Merge pull request #284 from CoreMedia/JENKINS-24787

[JENKINS-24787] Removed unnecessary undocumented methods in Gerrit trigger
Added support for Jenkins Notification Plugin.
Added documentation.
cleanup, added parameter validation
Merge remote-tracking branch 'origin/gerrit-events'

Conflicts:
	docs/Home.md
Merge pull request #286 from CoreMedia/spock-only

Converted all tests to Spock
JENKINS-21328 - support test stability publisher
JENKINS-21328 - support test stability publisher (documentation update)
added context for test data publishers