Fix group add/remove member inconsistencies.

This fixes some of the inconsistencies with groups.

1. should display error message if all the members in the group are deleted rather than silently failing.
2. resolve the issue when a member is deleted and added back in one update action.
3. increase the max limit for number of groups displayes to 50 (until we have pagination for this)

There is no story/ticket for this in jira.