Remove extra backticks

Caused the key to be re-imported on every run. See https://github.com/stahnma/puppet-module-epel/issues/1
Update test

See commit 32e5b3c3c7fc3505e53ce9d9347b237764e81869
Update test

Fix commit 59d6ea73a75b3b7d1268075d09a13845fa412275
Merge pull request #6 from tOnI0/master

Remove extra backticks