[RFC] Reorganizing command names

This is just an proof of concept PR, so basically I propose to renmae the classes as follows:

````
./NodeMoveCommand.php
./NodeRemoveCommand.php
./NodeTouchCommand.php
./NodeTypeListCommand.php
./NodeTypeRegisterCommand.php
./WorkspaceCreateCommand.php
./WorkspaceDumpCommand.php
./WorkspaceExportCommand.php
./WorkspaceImportCommand.php
./WorkspaceListCommand.php
./WorkspacePurgeCommand.php
./WorkspaceQueryCommand.php
````

and that would then translate to the following command schema:

````
phpcr:workspace:purge
phpcr:workspace:import
phpcr:workspace:query
...
phpcr:node-type:register
...
phpcr:node:touch
...
````

Not sure if I have categorized things correctly, does `dump`,`import|export` etc belong in `workspace`?