New Collection class

It will replace Feed and will be able to handle most collections
WIP collections everywhere
remove special collections and just use Collection
WIP Feed (was Collection)

Rename Collection class to Feed again, Collection class name is better
used for objects with objectType 'collection', which confusingly
are the object items of api/user/<username>/lists/person

Removed PyPump.{Followers,Following,List}, can now be found as
Person.{followers, following, lists}
TODO: pypump/models/list.py needs to be rewritten to Collection class
Person: change set_cc
Collection class, will replace List
Lists and Collections

Collection.{add,remove,delete}()
Lists.create()
deleted pypump/models/list.py
Fix comments/likes/shares

Forgot to change from Collection to Feed in models/__init__.py when
renaming Collection to Feed
model._post_activity have a unserialize=bool which defaults to True, we
dont want to unserialize when response doesnt have same objecttype as self
Prevent exception in inbox on deleted collections
Merge pull request #63 from kabniel/collection

Feeds and Collections