add some dependencies, and fix Transrate curl

[macmanes]

No description provided.

[camillescott]

Thanks for your PR Matt! I was in the middle of making a lot of changes, so I ended up just folding these in under a different commit. I also made some major updates to the installation documentation and requirements via your and @ljcohen's suggestions -- it should install properly with a basic pip install dammit, and the documented installation methods and README all work. Given that, closing this and #18. Thanks again!