xitrum helper with concret class (get rid out of xitrum.Action)

Related to: https://github.com/ngocdaothanh/xitrum/issues/76
Discussion: http://groups.google.com/group/xitrum-framework/browse_thread/thread/912f4f81f88ba858

Changes in this pull request affects development mode of xitrum. In development mode all helpers of scalate templates will be concrete Action class not xitrum.Action. Also i look into xsbt-scalate-generate project to fit it into xitrum convention, and i found that it is extremely easy. I prepare the patch for it, i think xitrum team should fork this project patch and then publish it into sonatype repo (as xitrum-sbt-generate). After this we can get awesome templates where actions fields will be accessible directly, like in ruby and in my tests:

```scala
class MyAction extends Action {
 def some() = "some"
}

Scalate.renderSspString("<html><%=some()%></html>")(new MyAction())
```

Patch for xsbt-scalate-generate:

```patch
From 2b834dd9159168b136d3b65d4904303471d5b464 Mon Sep 17 00:00:00 2001
From: Aleksander Guryanov <caiiiycuk@gmail.com>
Date: Sun, 13 Oct 2013 18:58:46 +0700
Subject: [PATCH] Make helper concrete class (get rid out of xitrum.Action)

---
 generator/src/main/scala/Generator.scala | 17 +++++++++++++++--
 1 file changed, 15 insertions(+), 2 deletions(-)

diff --git a/generator/src/main/scala/Generator.scala b/generator/src/main/scala/Generator.scala
index 7dcda57..0372393 100644
--- a/generator/src/main/scala/Generator.scala
+++ b/generator/src/main/scala/Generator.scala
@@ -61,14 +61,27 @@ class Generator {
     paths collect {
       case Updated(uri, templateFile, scalaFile) =>
         val template = TemplateSource.fromFile(templateFile, uri)
-
-        val code = engine.generateScala(template).source
+        val code = engine.generateScala(template, extraBindings(uri)).source
         scalaFile.getParentFile.mkdirs
         IOUtil.writeBinaryFile(scalaFile, code.getBytes("UTF-8"))
         scalaFile
     } toArray
   }
 
+  def extraBindings(uri: String) = {
+    List(Binding("helper", uri2Class(uri), true))
+  }
+
+  def uri2Class(uri: String) = {
+    val aClass = uri.split('.')(0).replaceAll("/", ".")
+
+    if (aClass.startsWith(".")) {
+      aClass.substring(1)
+    } else {
+      aClass
+    }
+  }
+
   object Updated {
     def unapply(uri: String) = {
       val templateFile = new File(sources, uri)
-- 
1.8.1.2
```