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/controllers/helpers.go

@@ -0,0 +1,19 @@
+package controllers
+
+import (
+	"github.com/robfig/revel"
+	"html/template"
+	"time"
+)
+
+func init() {
+	rev.TRACE.Println("Registering helpers")
+	rev.Funcs["friendlyTime"] = func(t time.Time) template.HTML {
+		ty, tm, td := t.Date()
+		ny, nm, nd := time.Now().Date()
+		if (ty == ny) && (tm == nm) && (td == nd) {
+			return template.HTML(t.Format("03:04:05 PM"))
+		}
+		return template.HTML(t.Format("Mon Jan 2, 2006"))
+	}
+}