Add dynamically generated form used for range voting
Add macro to render the choices when confirming a vote
Update the range voting method to relying on a wtforms form

This adds CSRF protection to the voting pages and takes care of the data
validation directly in the form.
Adjust the range voting form to make use of the wtforms form created for it
Allow to vote up to the number of candidates
Fix the tests for the change in range voting
Rename get_voting_range_form to get_range_voting_form and VotingRange to RangeVoting
Add forms.get_simple_voting_form that dynamically generate the form for simple voting
Port the simple voting logic to use the forms just created
Adjust the simple voting template to rely on the form just added
Use candidate instead of candidates to be consistent with the old behavior
Ignore the [more] link for the candidates for the moment, we need a better solution
Fix the tests for the change in the simple voting processing and integration of wtforms
No layout change when confirming for the moment
If there is a usernamemap specified, use it instead of the field label
Fixed presenting the fields of the form with their appropriate label/value
Drop the cand_name dict as we already have the usernamemap dict
Fill in the usernamemap for all the candidates
The form now provides the candidate id directly as value (instead of its name before)
Allow to rely on the usernamemap also in render_field_in_row