3.0.0

## 3.0.0

- Changed ``twython/twython.py`` to ``twython/api.py`` in attempt to
make structure look a little neater
- Removed all camelCase function access (anything like
``getHomeTimeline`` is now ``get_home_timeline``) Fixes #199
- Removed ``shorten_url``. With the ``requests`` library, shortening a
URL on your own is simple enough
- ``twitter_token``, ``twitter_secret`` and ``callback_url`` are no
longer passed to ``Twython.__init__`` Fixes #185
    - ``twitter_token`` and ``twitter_secret`` have been replaced with
``app_key`` and ``app_secret`` respectively
    - ``callback_url`` is now passed through
``Twython.get_authentication_tokens``

[ci skip]
Update tests docstring

[ci skip]
Updating a lot of docstrings, EndpointMixin replaces api_table dict

[ci skip]
Automatically join kwargs passed as lists into comma-separated string

[ci skip]
Begin docs

[ci skip]
Making the docs pretty (I think?)

[ci skip]
Fix verify_credentials definition name

[ci skip]
Adding sexy doc theme ;)

[ci skip]
Activate that sexy theme ;P

[ci skip]
OAuth 2 support :)

[ci skip]
Attempting to make docs clear and understandable

[ci skip]
File coding, file description ALL THE THINGS

[ci skip]
Fork Me badge, more docs

[ci skip]
Custom sidebar

[ci skip]
Fixing code (errors from tests), update HISTORY

[ci skip]
… try this coveralls thing.
Attempting coveralls again.
Wearing the coveralls 8), Updating READMEs

[ci skip]
Introduce client_args

client_args allow for users to manipulate the request without our init
being cluttered up with keyword args

[ci skip]
Update docs to give examples for manipulating requests args