Remove unicode literals.

Lets start with this
Part of issue https://github.com/edx/diff-cover/issues/94

Based on django's docs we should just need to remove the u's. Though I have some gaps in my knowledge. I left a comment on an example where I am unsure if this works.
https://docs.djangoproject.com/en/1.5/topics/python3/#unicode-literals

This is where I am unsure. Is this fine? Or is the unicode literal required here?
If it is I don't see a great way to make it so.

This is my best plan
````
six.u("<div>Snippet with \u1235 \u8292 unicode</div>".encode("utf-8"))
````