Merge pull request #2 from asilx/master

Broken dependency problem  fixed
Started with tf layer on top of MongoDB logs

The layer is based on tfjava, but instead of reading input data from a topic, it reads transformations from the log data. Transformations can be queried using the same interface as for tf though.
fixing dependencies
added lookupTransform operating on top of MongoDB
date utility methods
refactored interface: tf now first checks if the frames and time points are in the buffers, and automatically loads transforms from the DB if not
removed warnings and unused code
added knowrob_cram package for ontologies related to the knowrob--cram integration
removed erroneous comments in pl files
fixed on-demand loading of transforms from DB, switched to faster jackson json library
draft for OWL classes describing CRAM concepts
Merge remote-tracking branch 'moritz/master'