update to Gradle 1.7
Implement SourceSets for Grails projects and expose to IDEA

Hook into IML generation to add Spring, Grails, and Hibernate facets
that IDEA creates when you import a Grails project. This only works
when running 'gradle idea'...Importing the project into IDEA via
the Gradle file uses the Tooling API which doesn't expose this data.
Install plugins to a known location outside of the build directory

This allows us to include the plugin source files into the source sets
so IDEA picks them up. Having them in build was problematic because you
cannot include a source directory that is a child of an excluded
directory.
change deprecated groovy declaration
Use single groovy version if provided with grails.groovyVersion

Ensures that only the specified groovy version is getting used
in this module regardless of dependencies. Useful when developing
against libraries that use a new Groovy version than the one included
in the version of Grails being used.
add a custom GrailsTestTask that allows for specifying testResultsDir
add phase and test.single support to GrailsTestTask
Add tasks descriptions and create some Java style task structure
add grails-test-app as dep to test and add input/outputs to GrailsTestTask
README updates