Add support for GROUP_MATCH_COUNT regex matching on category

Current support for regex matching was previously only available on the group.
Also, error reporting for regex failures has been added. In addition to this
feature enhancement a unit test has been written to check the regular expression
logic to ensure the count operation is working as expected.

(closes issue #16642)
Reported by: kobaz
Patches: 
      groupmatch2.patch uploaded by kobaz (license 834)

Review: https://reviewboard.asterisk.org/r/503/


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@247295 65c4cc65-6c06-0410-ace0-fbb531ad65f3