v3.0.0

This is a somewhat hasty release since a recent DNS change broke the ability to obtain new psiturk-org api credentials, meaning that the only way to use psiturk now is to host your own ad server. 3.0.0 has changes that make that a lot easier than 2.x, so I'm publishing this to pip so make that transition hopefully-smoother. v2.x will continue to work, as long as use_psiturk_ad_server is set to false.

🎉 Sorry for the headaches! Yay scientific progress! We will publicize this better, soon.