Update the default values and provide convenience methods for build stat...

...us 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.