Bugfix: OcStatusIndicator ID fixes

Inside the OcStatusIndicator, components were rendering the same IDs which resulted in invalid HTML. 
Since the clickhandler on the OcStatusIndicator also was refering to these IDs and they now are 
dynamically generated on the frontend, it has now been replaced with a computed 
property which receives the click target.

Also, the accessible description (only applicable to screen readers) has been 
changed from `<span>` to `<p>` which sounds better to the listener.

https://github.com/owncloud/owncloud-design-system/pull/1342
