OAK-510: Multivalued properties with array size 0 forget their type

Avoid losing type information when storing empty non-string arrays in the MicroKernel.
Also drop the PropertyDelegate.isArray() method in favor of the more generic getPropertyState().

git-svn-id: https://svn.apache.org/repos/asf/jackrabbit/oak/trunk@1482792 13f79535-47bb-0310-9956-ffa450edef68
travis: Skip the extra maven build. Add experimental web hook notification.

git-svn-id: https://svn.apache.org/repos/asf/jackrabbit/oak/trunk@1482793 13f79535-47bb-0310-9956-ffa450edef68