modify 'test show registered' cli output format

In order to improve readability, the output from 'test show
registered' has been modified to truncate fields to fit within
the format output if they are over a certain length.



git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@243242 65c4cc65-6c06-0410-ace0-fbb531ad65f3