Get back to mainsteam Jackrabbit implementation

At the moment, we use a forked Jackrabbit implementation. This patched Jackrabbit contains a number of fixes and augmentations that are required for specific Hippo functionalities or behaviors. This situation is undesirable therefor the subtasks of this issue lists all the patches contained in the Jackrabbit patch file.
This patchfile location is: <URL:http://svn.onehippo.org/repos/hippo/hippo-cms7/repository/trunk/jackrabbit.patch>