refactor(user): user_auth -> user_login
refactor(user): Rename methods for closer mapping to RPC API
refactor(user): Piazza -> rpc.PiazzaRPC
feat(dev): Add return_response kwarg to PiazzaRPC.request
feat(user): Allow instantiation of PiazzaRPC with no network_id
feat(user): Add login methods to Piazza
feat(user): Create a Network class
docs(user): Fix a few docstring
feat(user): Add get_user_profile to Piazza
docs(user): Fix docstring for Piazza.network
feat(user): Add methods to Network
feat(user): Add feed methods
docs(user): Fix some docstrings; do not raise NoNetworkIDError because request does not necessarily need one to be used
feat(user): Add feed_filters property to Network for easy access
feat(user): Implement iter_all_posts
docs(user): Add setup and more examples to README
docs(user): Add get_user_profile example to README
style(dev): Some PEP8-y fixes