2.0.1

This is the first bug fix release for the 2.0.0 series.

1. fixes a problem with assigning bonuses using the command line (worker bonus)
2. fixes a problem with the hit expire command
3. switches dependency from readline to gnureadline which should resolve issues for some people who had troubling getting readline compiled
4. other minor documentation fixes

As always type pip install psiturk --upgrade to get the latest version or install directly from the github master branch.