Make JBoss Snapshots Maven repository off by default

http://snapshots.jboss.org/maven2 repository [1] should be moved to a separate profile called snapshots that will be off by default.

[1] https://github.com/hawkular/hawkular-parent-pom/blob/b4daf82bd3b9d98c34fcd871cef3a0783b8c29de/pom.xml#L773-L783