Replace handling of 'all' special value for document tree valid children in PhpcrOdmTree with expansion in DI extension

These changes address the issue logged against the TreeBrowserBundle. The TreeBrowserBundle is being rewritten but this patches a couple of issues that current exist with the handling of the special 'all' value by expanding it to be an array of all types found in the document_tree config. This prevents javascript from having to know about how to handle the 'all' value and simplifies the PhpcrOdmTree logic slightly.

Also in this request the "undefined" node type which is added by PhpcrOdmTree is removed. This is only used for classes that you do not define in the document_tree config and really just provides a default icon.