Make the MeetMeAdmin N command (mute all nonadmins) not mute admins

(Closes Issue ASTERISK-19335)
Reported by: Johan Wilfer
Review: https://reviewboard.asterisk.org/r/1843/
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Merged revisions 361090 from http://svn.asterisk.org/svn/asterisk/branches/1.8
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Merged revisions 361091 from http://svn.asterisk.org/svn/asterisk/branches/10


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@361092 65c4cc65-6c06-0410-ace0-fbb531ad65f3