milkman.random

Hello Chuck!

First, thanks for your awesome module!

Second, sorry for my english.

Third, I have added some features to milkman, as "milkman.random" property. Some code can explain my idea:


	from milkman.dairy import milkman
	from myapp.models import Video, Editor
	
	# I just want a random video in the db to test with
	v = milkman.deliver(Video)
	
	# I want a video with a particular editor
	e = milkman.deliver(Editor)
	v = milkman.deliver(Video, editor=e)

    # I want a video with a random editor from exists
	v = milkman.deliver(Video, editor=milkman.random)

    # Force optional field generation
    v = milkman.deliver(Video, description=milkman.random)


Would you be added this pull request in milkman?