SLING-3031 : first use case of whitelabel support: the jcr node icon. The solution is rather minimalistic atm - will be more sophisticated as we see more use cases

git-svn-id: https://svn.apache.org/repos/asf/sling/trunk@1518224 13f79535-47bb-0310-9956-ffa450edef68
SLING-3030, SLING-3029, SLING-2985 and SLING-3032 : various new dependencies and imports added

git-svn-id: https://svn.apache.org/repos/asf/sling/trunk@1518230 13f79535-47bb-0310-9956-ffa450edef68