Adjust error message as per @ralphbean advices
Fix the unit-tests as we adjusted the error message

This ought to be the most tested piece of code in the project :)
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