remove redundant ioloop.install() calls

pep8 fixes
cleaning unused imports breaking tests

fix blocking code upon thread instantiation

bringing back non simple self explanatory syntax that will only confuse people ;), '_' is evil, I'm telling you.
Merge pull request #731 from gubatron/io-loop-install-cleanup

Io loop install cleanup
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.