Upgraded to Grails 2.2.1
Updated plugin dependencies

Updated all Grails plugin dependencies to the latest available versions.
Moved plugin dependencies from application.properties to
BuildConfig.groovy.
Changed version from 0.12 to 0.13
Moved unit test class to correct package
Fixed NPE when inferring next release env

Fixed problem where a NullPointerException was thrown when trying to
infer the next deployment environment for an application that is
associated with a system environment.
Prevent app release deployment if not possible

Under certain conditions an application and application release could
end up in a situation where it allows a user to see the deploy button,
but a deployment is not possible. Added a check to make sure that an
application release is deployable before showing the buttons.