It's part of the issue #20 (weird path on Windows). Django File class used
a full file path which resulted in path like C:\Example\pinry\static\C:\... which
is obviously invalid.
Factory Boy provides us with a better way of populating complicated
fields (like M2M relations) than overriding _prepare class method,
so we should be using them.
There has been issues when running a full test suite (for pinry and
the entire Django stack), and test fixtures are hard to maintain anyway,
so rewrite tests to use a Model mocker library (Factory Boy) to populate
database.
