ENH: Fail gracefully for version not found.
Merge pull request #994 from jseabold/safe-versions

ENH: Fail gracefully for version not found.
ENH: Print dateutil version.
Merge pull request #995 from jseabold/add-dateutil-version

ENH: Print dateutil version.
BUG: Handle combo of pandas 0.8.0 and dateutils 1.5.0
Merge pull request #996 from jseabold/fix-dateutil-parser

BUG: Handle combo of pandas 0.8.0 and dateutils 1.5.0.
Fixed incorrect arma_acf docstring
DOC: acovf -> acf.
Merge branch 'arima_process_docs'. Closes #819.

* arima_process_docs:
  DOC: acovf -> acf.
  Fixed incorrect arma_acf docstring