Add a stub file to find the zaptel headers in the right

place, rather than repeating the check on every single file.

Changes to the individual files are coming.

The header file name has been suggested by kevin.

Approved by: kpfleming



git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@51290 65c4cc65-6c06-0410-ace0-fbb531ad65f3