Add unit-test checking the behavior of the Election object on the D-day

These tests check the behavior of submission_open, election_open and
election_public on the day they occur to make sure we do not allow
the results to be public while the vote is still open
Prevent the election to be open when the results are public
Add an admin_review template that is read-only
If the election is open or public, review is disabled but page is accessible as read-only
No need for text field in the read-only version of the review page
Merge pull request #49 from fedora-infra/bugfix_review_ro

Bugfix & review read-only