Fix XML encoding of 'identity display' in NOTIFY messages, continued.

When r378933 was merged into 1.8, it should have also escaped
remote_display, since it will have the same XML encoding problem when
the caller/callee roles are reversed.

(closes issue ABE-2902)
Reported by: Guenther Kelleter
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Merged revisions 379001 from http://svn.asterisk.org/svn/asterisk/branches/1.8
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Merged revisions 379020 from http://svn.asterisk.org/svn/asterisk/branches/11


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@379021 65c4cc65-6c06-0410-ace0-fbb531ad65f3