The config files linked on common-UBlox GPS Cofiguration not working. They generate an error message line 51.
http://copter.ardupilot.com/wiki/common-ublox-gps/
Here are the links to the config files from the page:
Get the 3DR-Ublox.txt configuration file for Ublox6 or 7 here.
https://github.com/diydrones/ardupilot/tree/master/libraries/AP_GPS/config
For M8N the file is here.
https://raw.githubusercontent.com/diydrones/ardupilot/master/libraries/AP_GPS/config/Marco-Ublox_M8N.txt
I download the ublox config file from this page and it installed:
http://ardupilot.com/downloads/?category=29