add a method in BandStructure to get the direct band gap
add an option in RemoveDuplicatesFilter to also us symmetry in addition to the structure matcher
fix a small bug in SubstitutionTransformation. Sometimes the string method broke because it could not concatenate an object and a string
fix a few small bugs in substitutor and give the option to use symmetry to remove duplicates in addition to the matcher
Merge branch 'master' of github.com:materialsproject/pymatgen

Conflicts:
	pymatgen/alchemy/filters.py
Formatting adjustments.
Simplify DuplicateRemoval code.
Change default tolerance to 0.6.
Add circle.yml.
Switch order of installation process.
Remove matplotlib from requirements.txt
Set pip install to quiet mode.
More fixes to circle file.
Improve circle test coverage.
Scipy can't be pip installed.
Remove INCAR tag checking.
Merge branch 'master' into mapi2