Fix source specs to test all key permutations
Fix source specs to test all key permutations

Previously only one should in each block was being evaluated. This moves each
should to its own block so that all values are tested. It also adds another set
of params so that all useful permutations of key, key_server, and key_content
are generated. It also replaces the previous ternary assignment for param_set
with a hash merge.

imphil/puppetlabs-apt,imphil/puppetlabs-apt,zoide/puppet-apt,puppetlabs/puppetlabs-apt,gwdg/puppetlabs-apt,gizmoguy/puppetlabs-apt