Add Cache Key Param to Entry CSS Link

Make sure the URL of the entry stylesheet changes on publication so
static assets can be cached by a CDN.
Add placeholder partial to add analytics to editor.

app/views/pageflow/editor/entries/_analytics.html.erb can be provided
in an Pageflow application to add analytics tracking to the editor.
Use teaspoon for javascript testing

Conflicts:
	Gemfile.lock
Javascript specs
Editor API: Adds base API for editor features/add initializers.

The pageflow.EditorApi class and the instance pageflow.editor provitde a
way for additional/external features to access editor.features.

 * Adds API for registering initializers.
 * let editor extensions navigate to paths
Editor API: Register additional menu items.

Lets editor extensions add Menu Itemsto be displayed on the root sidebar view.
These can use the a a data-path attribute to set the path to be navigated to.
Editor API: Register additional router and controller for sidebar.

This lets editor extensions register backbone router and controller
objects that will be instatiated when the editor is intialized.
Editor API: adds api for file selection.

Editor extensions can register handlers to re-use the file-selection
view to get files to use in custom models/new page types.

The files view can be invoked via API(pageflow.editor.selectFile).
Register models in engines to be associated with an entry/revision.

Authors of extensions/new page types can use this API to
register active records models to be associated with entries.
Editor API: Adds an API for the access to the failure UI and retry-functionality.

Extensions of the editor can use pageflow.editor.failures.watch to observe
collections and display errors in the UI on the top of the editor.

Additionally its possible to subclass pageflow.Failure and use
pageflow.editor.failures.add to have them displayed in the UI.
Stub of documentation on how to add page types
style for backbutton
Fix for updating of pagetype config in editor.
Autoplay option for video and audio pagetypes
Fix for TestPageType
Merge pull request #93 from tf/editor-analytics

Add placeholder partial to add analytics to editor.
Merge pull request #94 from tf/entry-css-cache-key

Add Cache Key Param to Entry CSS Link
Merge pull request #95 from tf/no-autoplay

Make Autoplay Configurable for Audio and Video Page
Merge pull request #96 from tf/new-editor-api

Editor JavaScript API