SLING-3979 - [tooling] multi valued properties are still not correctly
exported to the server

Use a better means of detecting whether the property definition matches
what we want to write and delete the existing property if it does not.

git-svn-id: https://svn.apache.org/repos/asf/sling/trunk@1628836 13f79535-47bb-0310-9956-ffa450edef68