Add pickle test for structures. Remove singleton decorator for PT.
Fix pickling for periodictable.
Revert "Fix pickling for periodictable."

This reverts commit a8df86f9ab23f4b8df297e5dc58ef86f5b61381a.
Fix Pickle Test.
Pull changes from stable_py3.
Increment monty req. Refactor to use monty.functools.lazy_property.
Adopt best pratices in opening files with "rt" / "wt" for text files in vaspio.
Add POSCAR writing test.
More fixes to file writing.
Make sure all Vasp input files are done in unicode.
Increment monty requirements.
More unicode fixes. and cleanup.
Make sure cifio uses unicode.
Unicode fix in xyzio.
More unicode conversions for cssr.
unicode fixes for qchemio.
Fix pmg load.
Use from __future__ import unicode_literals to execute default unicode all over
pymatgen.
Fix Cifio conversino.
Unicode fixes.