TST: dtype issue in test_groupby.py on windows
Merge pull request #5598 from pydata/winfix3

TST: dtype issue in test_groupby.py on windows (GH5595)
BUG: reset setitem_copy on object enlargement
TST: eliminate SettingWithCopyWarnings in tests (catch them)
TST: tests for GH5597
TST: add testing base TestCase to provide global testing config
TST: changed refs to use testing/TestCase where setUpClass/tearDownClass are defined
TST: change from using unittest.TestCase directly to using pandas.util.testing.TestCase