res_pjsip_phoneprovi_provider: Fix reload

Reloading wasn't working correctly because on a reload, the sorcery apply
handler was never being called for unchanged users.  So, instead of using
an apply handler, I'm now iterating over all users.  Works much more reliably.

Tested-by: George Joseph

Review: https://reviewboard.asterisk.org/r/4288/
........

Merged revisions 429914 from http://svn.asterisk.org/svn/asterisk/branches/13


git-svn-id: http://svn.asterisk.org/svn/asterisk/trunk@429915 f38db490-d61c-443f-a65b-d21fe96a405b