Shining up README and adding full reference

[RasmusFonseca]

People googling the paper title might find it useful to have the github repo show up in the search results

[davidhallac]

Thanks! This is very helpful. (The one slight change I made is to remove the "pip install" comment, since the Pypi version of TICC is the "blackbox" branch, rather than the "master" branch). But other than that, it looks great!