improved readme

Correctly formatted the code snippets, lowered some of the all caps, and moved the section about accepting jobs into the appropriate place for reading as you work through the process. That last bit does mean the use of ``list_jobs.py`` is split by the accept step, but seems worth it; less scrolling and switching back and forth. 

Also removed the reference to the serviceUserName field in the POST payload since that is deprecated. 

Also installed the github selfies chrome extension, because... selfies.

![selfie-2](http://i.imgur.com/jJrdT5B.gif)