Better documentation

0.3.1

comment

Fixed crashing bug when taskDescription sometimes comes back nil

internets seem to suggest taskDescription is persisted, but in practice we see it coming back nil sometimes so we fall back to a header:
http://stackoverflow.com/questions/24500545/checking-which-kind-of-nsurlsessiontask-occurred

First cocoapod release

Tested against testflight sdk logging in our app with 150 users, looks to work predictably and at the very least not cause any problems