Workspace Node Update Command and fixes

- This command updates multiple nodes in a workspace based on a given
  SQL query.

````
./bin/phpcr workspace:node:update "SELECT FROM nt:unstructred" --set-prop=foo=bar --add-mixin=some:mixin
````

Follows same options as `node:touch`. There is also room for adding a `workspace:node:remove` command for selectively removing nodes from a workspace.