Pytest plugin to randomly order tests and control random.seed.

Features:
* Randomly shuffles the order of test items. This is done first at
the level of modules, then at the level of test classes (if you
have them), then at the order of functions. This also works with
things like doctests.
* Resets random.seed() at the start of every test case and test to
fixed number - this defaults to time.time() from the start of
your test run, but you can pass in --randomly-seed to repeat a
randomness-induced failure.
* If factory boy is installed, its random state is reset at the
start of every test. This allows for repeatable use of its random
'fuzzy' features.
* If faker is installed, its random state is reset at the start of
every test. This is also for repeatable fuzzy data in tests.
* If numpy is installed, its random state is reset at the start of
every test.