res_phoneprov add snom 300, 320, 360, 370, 820, 821, 870 support

(issue #18713)
Reported by: lathama
Patches:
     snom_dir.diff uploaded by lathama (license 1028)
Tested by: lathama


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@305988 65c4cc65-6c06-0410-ace0-fbb531ad65f3