Adds dash/panel app templates, mgmt commands, template loader.

Implements blueprint scaffolding.

Using custom management commands you can now create the majority
of the boilerplate code for a new dashboard or panel from a
set of basic templates with a single command. See the docs
for more info.

Additionally, in support of the new commands (and inherent
codified directory structure) there's a new template loader
included which can load templates from "templates" directories
in any registered panel.

Change-Id: I1df5eb152cb18694dc89d562799c8d3e8950ca6f

horizon/templatetags/horizon.py

@@ -132,13 +132,16 @@ class JSTemplateNode(template.Node):
 
     def render(self, context, ):
         output = self.nodelist.render(context)
-        return output.replace('[[', '{{').replace(']]', '}}')
+        output = output.replace('[[', '{{').replace(']]', '}}')
+        output = output.replace('[%', '{%').replace('%]', '%}')
+        return output
 
 
 @register.tag
 def jstemplate(parser, token):
     """
-    Replaces ``[[`` and ``]]`` with ``{{`` and ``}}`` to avoid conflicts
+    Replaces ``[[`` and ``]]`` with ``{{`` and ``}}`` and
+    ``[%`` and ``%]`` with ``{%`` and ``%}`` to avoid conflicts
     with Django's template engine when using any of the Mustache-based
     templating libraries.
     """