Added message: as an option for the service, as Grails now supports this in it's message implementation for Controller/Taglib artefacts. Now includes a unit spec to make some basic tests.

Did a cleanup of the plugin, bumped it to version 0.9 and encourages the plugin author to release it as 1.0
Plugin as 1.0-SNAPSHOT
Merge pull request #3 from sbglasius/add-message

Add message