Change: Don't fallback to appId in case the route of file action is not defined

When opening a file in a editor or a viewer the path was falling back to an appId.
This made it impossible to navigate via the file actions into an app which doesn't have duplicate appId in the route.
We've stopped falling back to this value and in case that the route of the file action is not defined, we use the root path of the app.

https://github.com/owncloud/product/issues/69
https://github.com/owncloud/ocis/issues/356
https://github.com/owncloud/web/pull/3740