Added option to set filename manually



Added an option to allow you to determine the name of the file in the sudoers.d folder yourself, instead of automatic naming.

I was having issues where the sudoers file created by foreman (called foreman-proxy) was deleted since I had purge enabled. I would like to keep purge enabled, but I need the foreman-proxy file to remain (obviously) or I wont be able to manage my puppet certificates from within foreman.
added documentation for sudo_file_name option
added option to sudo::conf table
Merge pull request #73 from netson/master

Added option to set filename manually