Compile the NRPE plugin for source server installs with package client installs

Source + Source would give us the NRPE plugin, but if a user installs
just the server by source (to get the latest version that Debian/Ubuntu
don't ship) they wouldn't get the NRPE plugin and Nagios wouldn't work.
Break out NRPE compilation to avoid duplicate code

NRPE installs are the same except for 1 line.  Just use an if statement
to changet that single line
Remove duplicate code

Add tar to the packages to include on the server install (it should
have been there anyways) to allow us to remove all the package /
build-essential stuff.  This already exists in both of the recipes that
would call this recipe.  No need to do it twice.