BUG: set_names should not change is_ relationship
Merge pull request #5132 from jtratner/fix-set-names-error

BUG: set_names should not change is_ relationship
CLN: add a different locale for non slow tests
CLN: clean up common.py
CLN: clean up imports
CLN: assign figure to a variable
CLN: clean up tslib a bit
TST/ENH: add locale testing utils
CLN: remove unnecessary stuff