Working Rg code
Added angle.py
added contact
docstring update in contact
Preliminary Numpy implementation of dihedral
Added n_residues property.  Docstrings to dihedral.py
Sanity check for phi psi indexing
Added tests for dihedral.  A few minor fixes for robert.
Finally fixed dihedral with passing tests
Added internal.py and change XYZList to xyz etc
Fixes for robert
Fixed bug internal.py and renamed MSMBuilder to mdtraj
Added scipy req to travis
Added networkx to travis
Flexible offset syntax
Hopefully fixes chain / residue stuff
Consistent names
Merge pull request #44 from kyleabeauchamp/geometry_port

[WIP] Porting geometry