[RFC] 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 /"
$ php app/console phpcr "node-type:list"
$ php app/console phpcr "SELECT * FROM [nt:unstructured]"
````

Unfortunately I do not know if it is possible to bypass the argument parsing so that we can remove the quotations.

Also, the `phpcr-shell` is currently missing an equivalent for the `update` command
PHPCR Shell requires the user to manually call `save` in a shell session, so we do it manually here. In the future the shell should have configuration for automatic flushing and an API for turning that on and off.