Added SSL support in GeventConnection

* Calling ssl.wrap_socket() if ssl_options are given
* Removed useless select() code in the read and write greenlets, that
  was causing weird deadlocks in SSL mode
put back select() calls in gevent read/write loops
properly drain pending data on SSL socket in the gevent reactor
cleanup
Merge remote-tracking branch 'flupke/gevent-ssl' into PYTHON-174
generalized read loop in favor of ssl-only 'drain'

tweaking gevent ssl PR WIP
Remove extraneous file from git.
Merge pull request #216 from datastax/PYTHON-174

Python 174 - Gevent SSL