Update dependencies and instructions

Hey!

First of all, thanks for making such a cool project! I've been trying to come up with a way to run a Core Wars league with friends, and this definitely seems like the most accessible way to get new friends into it.

I went to set up an instance of this, and found it a bit difficult to figure out. I made a few changes to make it a bit more accessible:

* Froze all the python requirements in a requirements.txt file
* Updated the way Flask-WTF is imported to reflect changes to the library
* Updated the `assets.py` script to make sure the paths are correct
* Add a versioned, static copy of the `angular-d3` library, since it doesn't appear to be available in Bower anymore
* Added setup instructions to the README