Use $url param to build apt-key url

When using a mirror of sensu I want to also
use the mirror to retrieve the repo's apt-key,
particularly if there's no internet available.

Author: patdowney

manifests/repo/apt.pp

@@ -34,7 +34,7 @@
 
     apt::key { 'sensu':
       key         => '7580C77F',
-      key_source  => 'http://repos.sensuapp.org/apt/pubkey.gpg',
+      key_source  => "${url}/pubkey.gpg",
     }
 
   } else {

spec/classes/sensu_package_spec.rb

@@ -61,6 +61,11 @@
           context 'override repo url' do
             let(:params) { { :repo_source => 'http://repo.mydomain.com/apt' } }
             it { should contain_apt__source('sensu').with( :location => 'http://repo.mydomain.com/apt') }
+
+            it { should contain_apt__key('sensu').with(
+              :key         => '7580C77F',
+              :key_source  => 'http://repo.mydomain.com/apt/pubkey.gpg'
+            ) }
           end
 
           context 'install_repo => false' do