Add counters for when descriptions are too long

[aleksisalonen]

Add counters to the short description, description and Venue additional information fields that inform the user by how much the allowed character limit is exceeded.

Before hitting the maximum characters the counters should function as is. After the maximum amount of characters the existing counter should be replaced by the notification:

"Kuvaus on [exceeding character counter] merkkiä liian pitkä."
"The description is [X] characters too long."

For example, in the short description field, a 180 character input should produce the notification:

"Kuvaus on 20 merkkiä liian pitkä."