I'm getting into trouble while trying to reuse this class in a multiple
inheritance context because the proper __init__ method is never called.
So, let's get rid of __init__ in Paginable and implement 'limit',
'offset' and '_has_next' attributes, previously defined in __init__ as
reified properties. Notice that, since _has_next may be changed (in
paginate() method), we also need a setter for this property.

Accordingly, drop super() calls in resource classes inheriting from
Paginable and mention that this class should be used as a mixin.