Add tests for committee pages

The committee pages are not really tested at all. There should be tests to check for things like:

- [ ] Current committee is shown on the main committee page.
- [ ] Past committees are shown in reverse chronological order on the history page.
- [ ] Future committees are hidden before the time they become the active committee.
- [ ] Both pages support an "April fools" mode, which is deactivated by default and can be activated by appending the `aprilfool` query parameter to the URL. This should show different pictures where members of the committee have an `april_fools_dir` set in the database, and fallback to the normal picture if this is not set.
- [ ] Pictures are loaded from the correct directories for each committee. Those with no picture should have text to specify there is no picture.
- [ ] The links generated by the `Mailto` component should also be tested. I have not established whether this is currently the case.
- [ ] Any members who are `april_fools_only` are only shown when april fools mode is activated.