Minor bugfix release

Add SASL support and minor fixes for 0.5.0 issues

Added support for Transactional Producer and V2 message protocol

Bugfix release. Fix memory issue with shield()

Stability bugfix before 0.5

Minor stability fixes

Debugging travis deploy

Rewrote Consumer internals, Records C ext

Bugfix release. Fix running under uvloop.

Full doc upgrade and added/fixed many consumer API's