Created libmod_mp to be library used by web server modules

This seperates the code dealing with webservers (apache httpd)
with the code that deals with indexers, database, and I/O
Clean up error_messages
-Renamed file header define
-Removed apache httpd code
Refactored code to build with libmod_mp instead of Apache HTTPD module

This is a continuation of overall refactoring and removing of
dependent code to a particular web server.
Added more testing for libmod_mp HTTP URI input