VDI UD workspace: grant/share, ungrant/unshare

[aurreco-uga]

(older related issue in #411 , unify)

1. the button to grant is also for ungranting (unclear )
2. we use two terms (share and grant ) in different places (eg column title "shared with"
3. what is "unknown"? date of sharing.. one needs to reload the page..
4. the process of ungranting does not provide feedback.. it might seem broken to the user..
5. new feature: enable adding a bunch of comma separated emails
   6.possibly a new name for isasimple