add a more complete gradle() command

add gradleName to gradleContext

gradle: add makeExecutable

gradle: convinience methods
gradle in gradlecontext form
format
Merge branch 'gradle-patch' into rxd

Conflicts:
	job-dsl-core/src/main/groovy/javaposse/jobdsl/dsl/helpers/step/AbstractStepContext.groovy
	job-dsl-core/src/main/groovy/javaposse/jobdsl/dsl/helpers/step/GradleContext.groovy
	job-dsl-core/src/test/groovy/javaposse/jobdsl/dsl/helpers/step/StepHelperSpec.groovy
increase visibility of ListView/jobNames field to protected