Initial setup for media manager application

As the media manager will be a quite complex component, we have to have
a solid foundation. This should it be.
Included:
 * Require.js (with text plugin)
 * Underscore 1.4.4
 * Backbone.js 0.9.10
Urgent bux fix in ChunkManager and made TwigConnector more secure

When moving the openForm-Method into the ChunkManager, there had to be
a way, that the ChunkManager knows, which Chunk is being executed.
Therefore there was a property currentChunk. Actually I forgot, that
there is also a container widget, so that the chunk manager has to
remember, that this chunk is still executed after a subchunk finished.
So now we are using an execution stack to solve this problem. The
container chunk also had to be modified, as there was the wrong method
called...
The TwigConnector was improved a little bit to only load functions,
that are "registered".
There are also some extra experiments for the media manager included.
Improved path clearing

We now remove 0-byte characters and ../.
We should only accept "absolute" URLs to prevent security issues.
ChunkManager and Asset follow L4-style

They're now using Service Providers and facades!
On the dashboard there are now some sortable boxes.
Chunks are now autoloaded without composer

For now the chunks are now autoloaded by the Laravel ClassLoader.
That's not perfect as it is performing a file_exists on every class it
loads. So it would be better to create an intelligent ChunkLoader,
which fetches a list of installed chunks (and can expand it on it's
own), but therefore we first of all have to finish the chunk structure
etc. So there is now no "composer dumpautoload" needed anymore for
adding a new chunk. Yay! :)
Bugfix in MediaController and in TwigConnector

On some hosts (PHP 5.3 ones) the MediaController had some errors while
resolving the external path. These issues are now fixed. Also there was
a bug in the TwigConnector that only occurs on PHP 5.3 due to
differences in the closure scope.
Tidied up ChunkManager and hopefully fixed a bug in the FileSystem
Merge branch 'master' of https://github.com/dbohn/cmex into userAdministration
Minor changes