Enhancement: Improve resource loading within spaces

We've improved the loading of resources within a space. This enhances performance and overall stability within spaces.

* The loading task will determine if a space needs to be fetched or not. Route changes within a space do not require the space the be fetched again. This also ensures that the space image and readme won't be fetched when navigating into subfolders.
* The space now gets set at the end of the loading task. This ensures that the space task has finished as soon as the image and readme get loaded.

https://github.com/owncloud/web/pull/6601
