With the addition of this patch two new defines will be added; one to
manage APT configuration files (apt::conf) and one that abstracts out the
requirements needed to turn on backport repositories (apt::backports).
In addition, the patch takes the opportunity to clean up variable
definitions so they follow a consistent pattern of setting local
variables to the fully qualified value stored in the apt::params
class. Previously all variable used within a class directly addressed
the apt::params namespace when ever the variable was used. In the
pattern they now adhere to we can more easily switch the namespace
data lives in or externalize it even more using hiera.
