Implemented support for user templates

Added a way for users to upload their own "art" and use it. Also edited the README.md to describe the changes and file format.

One unrelated note: I'd highly suggest moving the things you have in development to a separate branch. This could be done with the following commands:

```
git branch dev
git rm -r eric gitfiti.html gitfiti.js gitfiti_web.py text.html views
```

This allows the main branch to be a little less cluttered.