Improved sudo management

* Set the puppetrun sudo command to match the user specified using puppetrun_user parameter
* Only manage the sudo rules if both puppetca and puppetrun are enabled

This is a refactor of #101 

The spec tests fail on my desktop, could use second pair of eyes as it appears like it shouldn't be failing.
I was unsure the best route to go about it.  I can think of either using a series of if/elsif/else statement(s) or using variables that contain the array elements that correspond to the puppetrun and puppetca "changes" and merging to result in the final array.