Fixed add_key stalling indefinitely, and test code leaking into production setting
Removed apt_key tests, as they didn't test the real functionality.

Tests used heavily mocked version of the apt_key code, which meant that
it didn't properly test real life scenario.
Merge pull request #1913 from jlitola/apt_key

Fixed apt_key's add_key stalling indefinitely, and test code leaking into production