Sketch metis implementation of PreQL GROUP operation
Make group sequential by default
Clean up group.py
Update install scripts for pymetis
Add libboost-python-dev for pymetis
Pin to python protobuf<=2.5.0
Merge branch 'master' into group-metis
Port tarot tests for group
Merge branch 'group-metis' of github.com:priorknowledge/loom into group-metis
Pep8 compliance
Update licenses
Fix group_sample bug
Merge pull request #66 from priorknowledge/group-metis

Implement PreQL GROUP operation using metis consensus clustering