Add a trigger for comment containing a specified RegEx

This patch add a trigger that will trigger jenkins build on comment containing
a specified regular expression.

This can be usefull for user to specify a comment to run a build (eg.  Please test this )
Merge pull request #170 from criteo/comment-contains-regex-feature

Add a trigger for comment containing a specified RegEx
Update GerritTrigger.java

Changed back the logging of comment added is interesting to trace.
Revert accidentally changed log level

Previous change changed trace log level to info. Revert it.
Merge pull request #171 from criteo/comment-contains-regex-feature

Revert accidentally changed log level
[maven-release-plugin] prepare release gerrit-trigger-2.12.0-beta-4
[maven-release-plugin] prepare for next development iteration
Don't trigger builds triggered by the same event

Now any builds are triggered even if existing builds triggerd by the same
event are running.

This patch prevents to trigger build according to the below policy:

* Project has triggered/running build triggered by the same event.
* The event trigger builds has still running build.

This would fix JENKINS-24445.

Fix for JENKINS-24445

Task-Url: https://issues.jenkins-ci.org/browse/JENKINS-24445
Merge pull request #172 from rinrinne/running-trigger

Don't trigger builds triggered by the same event
Don't keep Extension instances

All instance of Extension extended class must be fully managed by
Jenkins instance. So those must not be reused by other instances.

This patch fixes such issue. Targets are:

* ToGerritRunListener
* DependencyQueueTaskDispatcher

Fix for JENKINS-24575

Task-Url: https://issues.jenkins-ci.org/browse/JENKINS-24575
Fix checkstyle error

This patch increase the threshold of file length.
Permanent fix is to be refactored, but it is out of scope for this
change.
Add spec test
Checks list is empty or not
Merge pull request #175 from rinrinne/extension-instances

Don't keep Extension instances
Updated my contact info
Log when instance is not found
Fix session management in manual trigger page

In ManualTriggerAction, session is always created if nothing.
It might be issue if session is closed before build.

This patch creates session once then reuse it.

Fix for JENKINS-19013

Task-Url: https://issues.jenkins-ci.org/browse/JENKINS-19013
Merge pull request #176 from rinrinne/session-manage

Fix session management in manual trigger page
Provide notification level to gerrit command

Now notification level feature is provided to REST API only.

This patch provides this feature to Gerrit command as parameter
named 'NOTIFICATION_LEVEL'.

Note that this parameter always 'ALL' at build started.
It's a default value if ReviewInput has no Notify attribute.
Merge pull request #177 from rinrinne/notify-for-ssh

Provide notification level to gerrit command