Problem ======= A contextual string is passed to FlagUsageError, while the standard 'message' field is unused.
Problem
=======
A contextual string is passed to FlagUsageError, while the standard 'message' field is unused.

Solution
========
This small change exposes the usage string as the message as well.

RB_ID=775482

edombowsky/util,edombowsky/util,folone/util,edombowsky/util,BuoyantIO/twitter-util,folone/util,twitter/util,twitter/util,folone/util,BuoyantIO/twitter-util,twitter/util,edombowsky/util,folone/util,BuoyantIO/twitter-util,BuoyantIO/twitter-util