removed check_login from db mixin
added models and migrations for openid plugin
modified auth/__init__ hooks to work better with multiple plugins. Removed auth/lib.py. And added a basic_extra_verification function that all plugins will use.
Modified basic_auth plugin to work with modified auth plugin hooks. Added context variables. Removed basic_auth/tools which was previously renamed to basic_auth/lib.
added a register_user function to be able to use in a plugin's register view, and modified auth/views.register to redirect to openid/register if appropriate.
openid plugin v0, still need to authenticate via openid.