Allow 'seen' date to be given somewhere

[dracos]

"Not sure what, if any, solution there might be for this. Profiles are in date order for the shows, which is fine when the run isn't too long, but some London shows last for years. I'm not sure what the best approach is but I'm fed up of seeing War Horse at the top of my profile. Can Shows that last over a year have an extra box where people can add month/year they visited?"