Dynamic limit of event description field

[ebartz]

Is your feature request related to a problem? Please describe.
It would be nice if the frontend takes te actual size of a database field into account.

For instance, the limit for the description of an event is currently hard coded to 2048, while the database field could be larger:

alf.io/src/main/webapp/resources/angular-templates/admin/partials/event/fragment/edit-event-header.html

Line 57 in c13e448

<textarea data-ng-model="obj.description[allLanguagesMapping[langValue].locale]" name="description-{{allLanguagesMapping[langValue].locale}}" id="description" required class="form-control" data-ng-minlength="10" data-ng-maxlength="2048"></textarea>

Describe the solution you'd like
The application could check on startup how big the database field actually is.

Better solution
Let the user increase the limit in the admin backend and actually perform the change on the database if needed.