Add a fix for router so it correctly handles data of type text/plain under Python 3.
Add a fix for router so it correctly handles data of type text/plain
under Python 3.

Input body is actually bytes under Python 3, but we except and work with
text type (str / unicode) so we need to convert from bytes to unicode.

nzlosh/st2,StackStorm/st2,Plexxi/st2,Plexxi/st2,Plexxi/st2,StackStorm/st2,StackStorm/st2,nzlosh/st2,StackStorm/st2,nzlosh/st2,nzlosh/st2,Plexxi/st2