Add a rollover count so limits are obeyed

Limits in file size don't seem to obey unless set to > 1.
More sane logging level by default
Merge pull request #721 from hoffmabc/fix-logging-i

Fix logging issues
Flag implicit relative imports (W0403).
State relative imports explicitly.

* Reorder imports in accordance to PEP8.
* Replace calls to privtopub with calls to
  privkey_to_pubkey for consistency.