Log Message:
Update py-libmc to 1.2.3.

Changes in 1.2.x:
- 'sevmer.org'__ versioning scheme
- Fixed GIL issues
- Added CAS support (ketralnis)
- Added SASL authentication (Remoun)
- Added more detail to errors (spladug)
- Added mapping-like behavior for clients
- Fixed build errors on Mac OS X
- Moved to nose__ for testing
- Added ''auto_eject'' behavior
- Added ''num_replicas'' behavior
- Added ''remove_failed'' behavior
- Removed ''cache_lookups'' behavior
- Improved repr of clients (noah256)
- Improved IPv6 support (JshWright)
- Improved pooling behavior so it doesn't cause lock-ups
- Improved tests and testing foundation
- Improved documentation and structure
- Internalized Sphinx documentation
- Bunch of other stuff