chan_sip: Send real CallerID information with P-Assserted-Identity (RFC-3325)

Prior too this patch, the P-Asserted-Identity header would include anonymous
caller id information which seems to go against the point of the
P-Asserted-Identity header. Now the real caller ID information will be
included in this header. Also, no privacy header would be included.
This patch adds 'Privacy: id' to outgoing SIP messages that include the
P-Asserted-Identity header.

(closes issue AST-1301)
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Merged revisions 411189 from http://svn.asterisk.org/svn/asterisk/branches/1.8
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Merged revisions 411190 from http://svn.asterisk.org/svn/asterisk/branches/11
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Merged revisions 411193 from http://svn.asterisk.org/svn/asterisk/branches/12


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@411194 65c4cc65-6c06-0410-ace0-fbb531ad65f3