adds 'p' option to PickupChan

The 'p' option allows the PickupChan app to pickup
a ringing phone by looking for the first match to a
partial channel name rather than requiring a full match.

(closes issue #16613)
Reported by: syspert
Patches:
      pickipbycallid.patch uploaded by syspert (license 938)
      pickupbycallerid_v2.patch uploaded by dvossel (license 671)
Tested by: dvossel, syspert




git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@250141 65c4cc65-6c06-0410-ace0-fbb531ad65f3