Imports from __init__.py confusing for intersphinx

[cblegare]

Sphinx (using intersphinx) can't find some classes from your objects.inv, resulting in

WARNING: py:class reference target not found: flask_restplus.api.Api

because it is referenced as flask_restplus.Api and not flask_restplus.api.Api in the objects.inv

This can be worked around by assigning the __module__ property of classes imported in any __init__.py. See also http://stackoverflow.com/a/24787344

[cblegare]

See sphinx-doc/sphinx#5603

[cblegare]

Closing in favor of issue in sphinx (mentioned above)