renamed GrailsPluginDbHelperRestGrailsPlugin to DbHelperRestGrailsPlugin so the plugin name will be db-helper-rest and not grails-plugin-db-helper-rest
dropped the minimum Grails version to 2.0
deleted unused files
cleanup
added hibernate-core jar dependency so the code compiles; since users will likely have the Hibernate plugin installed, the will not affect the application
install-plugin is deprecated