Add default value for default templates

If a template has no type specifcation in it's name, then we use
'default' as map name now.

lib/zero/renderer.rb

@@ -61,12 +61,16 @@ module Zero
       search_files.each do |file|
         parts = file.gsub(/#{template_path}/, '').split('.')
         @templates[parts[0]] ||= {}
+
+        # Set default value
+        types = 'default'
+        # Overwrite default value, if it's set in template path
         if parts.count > 2 then
-          read_type(parts[1]).each do |type|
-            @templates[parts[0]][type] = file
-          end
-        else
-          @templates[parts[0]][''] = file
+          types = parts[1]
+        end
+
+        read_type(types).each do |type|
+          @templates[parts[0]][type] = file
         end
       end
     end

spec/unit/renderer/read_template_path_spec.rb

@@ -39,4 +39,15 @@ describe Zero::Renderer, 'read_template_path!' do
 
     it_behaves_like 'a template loader'
   end
+
+  context 'with default template' do
+    let(:file_list) {['foo/welcome/index.erb']}
+    let(:type_map) { {'default' => ['text/html', 'text/xml'] } }
+    let(:result) { {
+      'text/html' => 'foo/welcome/index.erb',
+      'text/xml'  => 'foo/welcome/index.erb'
+    } }
+
+    it_behaves_like 'a template loader'
+  end
 end