tls support

o mongoc_stream_tls integration - takes a mongoc_stream and does ssl
  over it
o mongoc-ssl - handles a bunch of interesting ssl features
  o CRL
  o common name verification
  o password protected pem's
  o rfc 6125 hostname verification
tls code review feedback integration

Addressing a bunch of little stuff (typos, style, etc)
Merge branch 'tls'