Adds support for the Groovy Postbuild script publisher plugin
fix indentation
Use an enum for the script failure behavior argument, rather than int.
- Move Behavior enum underneath PublishContext
- Add Behavior enum to auto-imported classes in DslScriptLoader
Merge remote-tracking branch 'sgtcoolguy/groovy_postbuild'

Conflicts:
	job-dsl-core/src/main/groovy/javaposse/jobdsl/dsl/helpers/publisher/PublisherContextHelper.groovy
	job-dsl-core/src/test/groovy/javaposse/jobdsl/dsl/helpers/publisher/PublisherHelperSpec.groovy