UI improvements for parameters (input and read-only) and model description.

Uses changes to swagger.js (swagger-client).

src/main/template/param_readonly_required.handlebars

@@ -3,7 +3,11 @@
     {{#if isBody}}
         <textarea class='body-textarea'  readonly='readonly' placeholder='(required)' name='{{name}}'>{{defaultValue}}</textarea>
     {{else}}
-        {{defaultValue}}
+        {{#if defaultValue}}
+            {{defaultValue}}
+        {{else}}
+            (empty)
+        {{/if}}
     {{/if}}
 </td>
 <td>{{{description}}}</td>