[WCM] Embedded PHPCR Shell

Replaces existing commands with embedded PHPCR Shell.

Depends on: https://github.com/phpcr/phpcr-shell/pull/40

For example

````
$ php app/console phpcr node:list / # commands with arguments can be entered without quotes
$ php app/console phpcr "ls -L2" # commands with options must be quoted
$ php app/console phpcr node-type:list
$ php app/console phpcr "SELECT * FROM [nt:unstructured]" # queries must be quoted
````

use ``%command.full_name%`` in the help text instead of ``app/console phpcr:shell``. Symfony does the replacement automatically (there is also ```%command.name%`` for just the ``phpcr:shell`` part). this way, you don't need to change the help when the command name changes (or when the user renames the ``app/console`` file to something else)