Documentation

I plan on writing some documentation on the specific information on the SDK's classes, methods and functions. I'll create this pull request now so I actually do it... It will be good to go once I make it through the checklist below. 

Feedback welcome :ok_hand:

- [ ] class facebook.GraphAPI
- [ ] get_object(id, **args) 
- [ ] get_objects(ids, **args) 
- [ ] get_connections(id, connection_name, **args)
- [ ] put_object(parent_object, connection_name, **data)
- [ ] put_wall_post(message, attachment, profile_id)
- [ ] put_comment(object_id, message) 
- [ ] put_like(object_id) 
- [ ] put_photo(image, message, album_id, **kwargs)
- [ ] put_object(parent_object, connection_name, **data) 
- [ ] put_wall_post(message, attachment, profile_id)
- [ ] delete_request(user_id, request_id)