add MP GGA VaspInputSet
Significant cleanup.
Yet more cleanup.
Still junking a lot more code.
More refactoring and code simplificaiton.
Remove useless GGA Config for MIT input set.
Merge remote-tracking branch 'mpmaster/master'
Merge branch 'master' of https://github.com/gmatteo/pymatgen
 Add support for suggested cutoff energies (abinit pseudopotentials)