CSHARP-671: server sometimes neglects to return setName causing the driver to think that the instance is not a replica set member and we remove it from memory preventing recovery.
CSHARP-603: GSSAPI on linux using libgsasl.
CSHARP-603: update for changes to driver authentication spec.
removed CRAM-MD5 and DIGEST-MD5 support.
corrected issue with SSPI utilizing cached credentials.  It is now required to specify the username for GSSAPI credentials.
fixing unit tests.