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
It'd be nice if you could make this ``**kwargs``. If necessary (i believe so?), also add a warning to the docstring that the exact params might differ between memcached libraries.