Add tests

[GuiltyDolphin]

Seeing as the installers need to work on various systems, it'd be really nice to have tests.

Not entirely sure how to go about this - perhaps testing some of the Perl custom-installs, e.g.,

./install/install.pl install emacs then assert that Emacs is installed.

It might be nice to auto-gen the tests for custom installers.

Things to test:

• [ ] Custom installers
• [ ] Linking
• [ ] Make recipes