Make all package name and ensure customizable

This makes all package names and package ensure values customizable as
parameters.  This is helpful for people who are not using vendor
provided packaging.  This also normalizes the package ensure value to be
'present' in all case.

Change-Id: Iee186f753b2800e59addd3f38591675fd5af35ad

spec/classes/designate_api_spec.rb

@@ -27,7 +27,7 @@ describe 'designate::api' do
         )
         should contain_package('designate-api').with(
           :name      => platform_params[:api_package_name],
-          :ensure    => 'installed'
+          :ensure    => 'present'
         )
       end
 
@@ -82,4 +82,22 @@ describe 'designate::api' do
 
     it_configures 'designate-api'
   end
+
+  context 'with custom package name' do
+    let :facts do
+      { :osfamily => 'RedHat' }
+    end
+
+    let :platform_params do
+      { :api_package_name => 'designate-api-custom-name',
+        :api_service_name => 'openstack-designate-api'
+      }
+    end
+
+    before do
+      params.merge!({ :api_package_name => 'designate-api-custom-name' })
+    end
+
+    it_configures 'designate-api'
+  end
 end