[WIP] Do not filter groups, but therefore update the user counts according to  the filter

On the users page, the groups are filtered at the moment. However, [we want  to leave them but update the users counts](https://github.com/owncloud/core/issues/9332#issuecomment-48380699).

We can turn on filtering  any time in the future again, the logic did not vanish. 

Fixes #9332 

@jancborchardt @raghunayyar @DeepDiver1975 

There  is not change in the group sorting, would we want this?