Update the default values and provide convenience methods for build status values in the gerrit trigger.

 - Create integer typed properties in the gerrit trigger
 - Update defaults for certain build status values to match defaults from gerrit trigger
 - Update the gerrit method to use the propertieds when setting build status values
 - Provide convenience methods for setting gerrit status values in gerritTrigger.
 - Add new test methods in test specification.
 - Update the GerritContext with convenience methods.

    def buildStarted(int verified, int codeReview);
    def buildSuccessful(int verified, int codeReview);
    def buildFailed(int verified, int codeReview);
    def buildUnstable(int verified, int codeReview);
    def buildNotBuilt(int verified, int codeReview);

  - Add another set of methods with signature
    build<Foo>(Object,Object) with code to coerce it arguments to int
    and call the corresponding build<Foo>(int,int) method.
JENKINS-18396
- Add ability to inject helper classes into GroovyClassLoader used to
  execute DSL code.
Merge pull request #60 from oesolutions/18396

JENKINS-18396
Fixing TopLevelHelper tests.
Merge pull request #61 from oesolutions/master

The tests for the TopLevelHelper are broken.
Add smaller git method signatures.
Allow an empty list of recipients.
Fix sendToRequester, made test to check.
Merge pull request #62 from quidryan/master

Fixing some issues found via mailing list.
Merge pull request #59 from bealeaj1214/gerritTriggerUpdates

Update the default values and provide convenience methods for build stat...
Implementation and tests for URL Trigger plugin
Added documentation
Merge branch 'master' into JENKINS-18462

* master:
  Fix sendToRequester, made test to check.
  Allow an empty list of recipients.
  Add smaller git method signatures.
  Fixing TopLevelHelper tests.
  JENKINS-18396 - Add ability to inject helper classes into GroovyClassLoader used to   execute DSL code.
  Update the default values and provide convenience methods for build status values in the gerrit trigger.
  Reordered parameters according to expected most frequent usage
  Removed default value for required argument Added tests for minimal and full call to sbt method
Changed spec method name to improve readability
Added missing test for text inspection
Fixed typo and removed (commented-out) development aid statement
Implemented DSL methods for advanced project configuration and for full timeout configuration support
Added implementation for blocking on up-/downstream builds
Removed DSL method for defining github project URL
Implemented build step for executing DSL jobs.