Add SSL support to mongo driver

The new options are passed in via the connection string.
Note that sslverifycertificate is 'nonstandard' but there is precedent: the .NET driver http://docs.mongodb.org/manual/tutorial/configure-ssl/#net
I tested and it works for me. I can give you a gist to download, compile, install mongo 2.4.9 with SSL; create a certificate; run the mongo server with SSL; if you desire.