Use Mark's new ast_str_case_hash function instead of jumping through hoops to...

Use Mark's new ast_str_case_hash function instead of jumping through hoops to do insensitive case lookups


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@156916 65c4cc65-6c06-0410-ace0-fbb531ad65f3