Many small refinements to front/backend UI

Changes:
 - Added a friendlyTime helper for nicer timestamps
 - Added validation to most action methods
 - Added error flash to several template files
 - Now making use to c.RenderError() to handle action errors
 - Removed message list slideUp() effect, takes too long
 - Fixed a problem with my vim indentation configuration, so CSS and
   HTML should be indented more consistently.

app/views/errors.html

@@ -0,0 +1,10 @@
+{{if .errors}}
+<div class="errors">
+  <p>Please fix the following errors and resubmit:<p>
+  <ul>
+    {{range .errors}}
+    <li>{{.Message}}</li>
+    {{end}}
+  </ul>
+</div>
+{{end}}