Minor Fix for GitSCM
Experimental Support for specifying the Git Branch, and shallow cloning (50 commits)
Added a SCM.option(String, Object = null) method to retrieve SCM options, and disabled the CrashReporter if the log level is set to debug.
Merge pull request #15 from DirectMyFile/develop

Implement SCM Options API, and add 'branch', 'clean', 'depth' options to GitSCM