mod_http_admin_api: restructure group-related info in API - Return the members of the group right in the get_group_by_id call. This is an O(1) of extra work. - Remove the groups attribute from get_user_by_name as that is O(n) of work and rarely immediately needed. The replacement for the group membership information in the user is for now to use the group API and iterate; future work may fix that.

# Introduction

This module sends a [version query][xep0092] to clients when they
connect, and logs the response, allowing statistics of client usage to
be recorded.

Note that since this is per connection, there will be a bias towards
mobile clients on bad connections.

## Example

    info    Running Running Swift version 4.0