BUG MultiIndex sometimes tupled on apply, 2902
Merge pull request #3199 from hayd/GH2902

BUG MultiIndex sometimes tupled on apply, 2902
Merge pull request #3204 from jreback/period_py3

TST: fix for tseries/test_period for py3k
CLN: refactor core/index and tseries/index,period to have their formats and to_native_types be consistent
     in naming / operation
ENH: add support for Period formatting (as a native type)
TST: add period support to makeCustomDataFrame for testing purposes
BUG/TST: format multi-index nan correctly