Added feature from bug #5573 and updated app_read

to be able to use indication tones, and argument 
parsing code. Documented possible problems this might
cause an older dialplans in UPGRADE.txt


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@7818 65c4cc65-6c06-0410-ace0-fbb531ad65f3