Create event unit tests.
Add date picker to event creation.

* UI design has to be fixed.
* Fork and change calendar behavior: it has to close when a date is selected.
* Reconsider screen ergonomy?
Auto-close calendar on date selection.
Changed date selection behavior.

Now: use of an inline single calendar and add selected dates in a summary.
TODO:
 * do not allow to select multiple times the same date;
 * manage date display (not good looking currently);
 * collect the dates on form submit (could be useful...).
Dead code.
Bugfix: selected dates were not added to the right container.
Code template readability.
Selected dates can be submitted (but do not pass validation yet).
UI.

 * Ability to remove selected date.
 * Removed bullet points.
Dead code.
UI date handling.

 * Sort selected dates (ascending).
 * An already selected date cannot be selected again.
 * Format submitted date.
Increase fields size.
Event: sort choices by date.
Dates (choices) from event are populated by a FINDER.byId(). Removed unnecessary code.
Event answer wiring.
Agregated event results.
Save event answer.