res_rtp_asterisk: Make the ICE transport check case insensitive as some implementations use 'udp'.

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Merged revisions 425360 from http://svn.asterisk.org/svn/asterisk/branches/11
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Merged revisions 425361 from http://svn.asterisk.org/svn/asterisk/branches/12
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Merged revisions 425362 from http://svn.asterisk.org/svn/asterisk/branches/13


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@425363 65c4cc65-6c06-0410-ace0-fbb531ad65f3