Make getUrlMapper protected

Reason for changing the getUrlMapper to protected is to allow me to write a plugin that will add custom end points to the selenium grid, which would allow me to stabilize my build on IE, plus allows me and other people to write plugins for the grid that most of the users might not want but some people will find useful. This gives us ability to setup a custom uri end point to pass info directly to the selenium server node on the grid, which would be unreachable in any other way.