Merge tag 'version/0.1.0' into develop

0.1.0
Refactoring code towards a more generic object structure. Most objects are a 'Thing' now (thing: name + id)
Added support for hot items
Updated changelog
Updated version
Generating the list of CollectionBoardGames when adding the items instead of when calling items()
Improved documentation
Switched classifier to beta
Added a new property to BoardGame, 'expansion' which indicates if this item is an expansion; the 'expansions' and 'extends' properties return list of 'Thing's
Added extra check for determining if an expansion is an expansion or the extended game
Keeping the expands and extensions lists "clean" so they can be properly serialized. Added methods for adding an expanded game or an extensions; the properties 'extends' and 'expansions' of BoardGame still return lists of Thing
Collection: if there's anything in kw['items'], add them from __init__
Properly adding extended games/expansions
Changed _add_game -> add_game
Adding any initial hotitems from kw['items']
Refactored _add_play -> add_play and adding any initial plays from kw['plays']
Made some User private methods public and adding any initial hot/top items
Raising BoardGameGeekError if missing any data when creating a Thing
Removed u'' prefix, added by mistake
Precomputing lists of buddies and guilds for an user instead of creating them when requested