Investigate porting viff to Gevent

[amiller]

There are some benefits to using gevent instead of twisted.
You can write your code in a more straight-line fashion, avoiding "callback hell". Functions like I/O and waiting for a queue are written as though they block, but actually yield to other greenlet threads.
My No. 1 reason to prefer gevent to twisted is that I find it easier to debug, since an except has a meaningful call stack.

• List out advantages/disadvantages of gevent vs twisted
• Determine which parts would be most difficult to port