(#201) Use root to exec

User root is needed to execute this command.

If someone changes the default Exec user, apt-add-repository will fail.
Change - to _

I did it to please my syntax validator, but I'm assuming it wasn't functioning as expected either.
Merge pull request #205 from braddeicide/master

fixed include, contained dash instead of underline.
Merge pull request #202 from tsuharesu/bug/exec_apt_ppa_as_root

Apt::ppa should exec with root
Convert existing tests over to beakr-rspec.
Merge pull request #206 from apenney/beaker-rspec

Convert existing tests over to beakr-rspec.
Add additional acceptance testing.

This work adds a test for every parameter in every class/define in apt.
Improve apt::force tests and ensure cleanup happens consistently.
Ensure apt::ppa fails on non-Ubuntu.
Fixes to make the tests run under Debian as well as Ubuntu.
Merge pull request #207 from apenney/add-params

Add additional acceptance testing.
Merge pull request #208 from apenney/ppa-debian

Ensure apt::ppa fails on non-Ubuntu.