Add g722 codec support to skinny

(closes issue ASTERISK-20788)
Reported by: snuffy
Tested by: snuffy, myself
Patches: 
    skinny-g722.diff uploaded by snuffy (license 5024)


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@378006 65c4cc65-6c06-0410-ace0-fbb531ad65f3