res_pjsip_phoneprov_provider: Provides pjsip integration with res_phoneprov

This module allows res_pjsip to integrate with res_phoneprov.  It handles
the pjsip 'phoneprov' object type.

Tested-by: George Joseph
Review: https://reviewboard.asterisk.org/r/3976/
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Merged revisions 425007 from http://svn.asterisk.org/svn/asterisk/branches/12


git-svn-id: http://svn.asterisk.org/svn/asterisk/branches/13@425008 f38db490-d61c-443f-a65b-d21fe96a405b