MP voting comparison WIP

#155 Still to do:

- [ ] Check comparisons where one (or both) MPs were tellers
- [x] Check correct ordering of votes (by date)
- [ ] Find the [actual difference](https://github.com/openaustralia/publicwhip/blob/9eef70833c06a56126010ebbf14f8daf3fbbf7ff/rails/app/controllers/members_controller.rb#L95) between "Votes Attended" and "All Votes" for MP comparison in the php
- [ ] Re-enable [these tests](https://github.com/openaustralia/publicwhip/blob/dfb6dbfc4cc02e2a0f03afa117a5d44f228c015e/rails/spec/requests/members_controller_spec.rb#L167) after fixing #150
- [ ] See if "show all" mode applies to vote comparisons