ENH: Import adfuller into tsa namespace
Merge pull request #1360 from jseabold/import-adfuller

ENH: Import adfuller into tsa namespace
ENH: Attach mlefit to results not model.
Merge pull request #1361 from jseabold/arma-attach-mle_retvals

ENH: Attach mlefit to results not model.
BUG: Fix typo.
Merge pull request #1363 from jseabold/fix-typo

BUG: Fix typo.