Update isntallation for Mavericks. Different commandline tools installation
procedure.
Fix examples page.
 Add YAML configuration file for PyFlowsScheduler.
Add Cs2O2 and Rb2O2 to the list of special formulas.
 Add support for PAW files in XML format.
Merge remote-tracking branch 'mpmaster/master'
 Add ref_file(s) methods to PymatgenTest so that we can easily get the filepath(s) used for unit tests
 Add pawecutdg variable to DeltaFactor workflow.