REF: Remove _pandas_mapping freq dict
ENH: Remove unneeded freq check
TST: Test pandas freq strings
TST: Test freq of predicted dates
BUG: Handle freq is None
STY: Don't catch exception in old-style way
Merge pull request #668 from jseabold/tsa-freq

Allow for any pandas frequency to be used in TimeSeriesModel. Closes #319.
ENH: Handle freq=None and improve errors in get idx.
TST: Test predict without freq in pandas index
BUG: Handle predict dates for pandas when freq=None
DOC: Update docs for predict when freq=None
STY: Clean up cruft
Merge pull request #714 from jseabold/fix-712

Fix dates for predict without freq. Closes #712.
TST: Add failing test for AR with named pandas.Series
BUG: Handle Series with names in make_lags
Merge pull request #722 from jseabold/fix-721

Handle pandas.Series with names in make_lags. Closes #721.
ENH: tools brentq_expanding, initial version
TST: add test asserts
REF: cleanup, remove unnecessary variables
DOC/TST: docstring, check case with start_low/start_upp arguments