Cleanup org.apache.jackrabbit.mk

imo we should clean up the org.apache.jackrabbit.mk.* packages that are currently
located in the oak-core module.

for me it is really hard to destinguish between code that is really part of the
productive code base for the oak project and code that is purely experimental
chunk and leftover.

in order to become familiar with the code that would be helpful for me and
anybody else that will contribute to the project.