Added support for SASL authentication in MemcachedCache, fixed FormParser bug, added support for python-binary-memcached

Support Additions:
- Memcached SASL auth
- Python binary memcached library

Bug fixes:
- Modified a FormParser test that was failing on account of a bad assertion
Also accept ``**kwargs`` here, and pass it to the ``Client`` class of each memcached library (not just pylibmc).