Various Puppet lint fixes

* Fix following warnings:
    * class not documented
    * double quoted string containing no variables
    * indentation of => is not properly aligned
    * string containing only a variable
    * top-scope variable being used without an explicit namespace
* Fix following error:
    * two-space soft tabs not used

Change-Id: I709b30e3d80c7cd3b22080a8c096a23342f75d2a