Use the configured formats for Gulp sessions if there are no joint formats...

Use the configured formats for Gulp sessions if there are no joint formats between requested formats and configured formats.

(closes issue ASTERISK-21756)


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@387545 65c4cc65-6c06-0410-ace0-fbb531ad65f3