Former members are listed confusingly in a committee's admin

Thom Wiggers
2018-01-17T20:01:39+01:00

The committee pages should only list current members

### Current behaviour

Current and former members are listed, which may be confusing.

### Expected behaviour

Only list current members.

### Steps to reproduce

1. View a committee with former and current members in the admin
2. See all of them