support multi language event and ticket category description

[syjer]

At the moment, there is a single field for the description.

[syjer]

TODO:

• let the user choose the supported languages in a given event
  • show only the selected locales in the top of the page
  • restrict the languages the user can have (server side)
  • restrict the languages the user can set in the ticket selection
• support multi language event description: need to add a table event_description(event_id_fk, locale, type, description): pk(event_id_fk+locale+type) : type is a discriminator (DESCRIPTION, ...). Will be used
• support multi language in the ticket category description: need to add a table ticket_category_decription(ticket_category_id_fk, locale, name, description) : pk(ticket_category_id_fk+locale)
• misc cleanup: migration scripts, others?

(Integrate I18nManager in the messageproperties handling?) still thinking to a decent strategy... Maybe based on a interceptor?

[syjer]

done.