Few formatting changes.

I have reviewed this module in Geppetto and it seems that there were some formatting issues that had it fail syntax checks. These changes included spacing which wasn't clear, as well as double quotations used when variables were not in the field. Double quotations should be used only when calling variables as per Puppet Documentation in both 2.7 and 3.0 Books. I have corrected these.

There is also an issue with the tests/unattended-upgrades.pp using a - instead of a _ for the test. unattended-upgrades class doesn't exist, while unattended_upgrades class does exist. I believe this is a change that was supposed to be put in but never was.