Keep the option to enlarge the images even if user has the maximum selected

This allows the user to still zoom on a specific image even if he has already made the largest
selection allowed. This would give the user the possibility to review other image and eventually
change the selection.
Merge pull request #5 from fedora-infra/keep_zoom

Keep the option to enlarge the images even if user has the maximum selected
Merge pull request #51 from fedora-infra/reviewers

Reviewers
Add a list of FAS group that will have a higher weight on votes
Ask the list of weighted voters groups when logging in
Add an utility method to check if the user if part of the weighted voters
Ignore this line from the test coverage
Add a value field to the vote table
Allow setting the value in the constructor of the Vote object
Adjust the `Vote.cnt_votes` method for the new model
Adjust the `Candidates.get_results` for the new data model
Adjust the `add_vote` method in the internal API to account for the new model
When processing votes, if the user is part of the designed groups, give its vote a higher value
Add unit-tests checking if a member of the designteam can vote fine
Add tests checking that the number of votes recorded fits the expectations
Add an alembic migration script to add the value column to the Votes table