Adds Subscription-State header to notify with call completion. per RFC3265

(Closes issue ASTERISK-17953)
Reported by: George Konopacki
Patches:
	19400.patch uploaded by mmichelson (license 5049)
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Merged revisions 349482 from http://svn.asterisk.org/svn/asterisk/branches/1.8
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Merged revisions 349502 from http://svn.asterisk.org/svn/asterisk/branches/10


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@349503 65c4cc65-6c06-0410-ace0-fbb531ad65f3