GRAILS_REPO_URL support for apps generated by profiles

[jdaugherty]

Issue description

forge, and all tooling except the profiles supports the notion of GRAILS_REPO_URL to force the addition of another maven repo (we use this to force the staging repo). The profiles currently do not have this concept, so the generated applications have to be manually modified. This ticket is to investigate adding such support to the profile if the env is set.