First shot in allowing unicode in URLs (cf #76)

Problem:

In [14]: print reverse("map", kwargs={'slug': u"академический", 'pk': 729})
/en-us/map/%D0%B0%D0%BA%D0%B0%D0%B4%D0%B5%D0%BC%D0%B8%D1%87%D0%B5%D1%81%D0%BA%D0%B8%D0%B9_729