Attempt to parse dates in non-ISO 8601 formats
We currently only accept dates in ISO 8601 format and print out a warning if the user puts in a date in a different format. We could make this part more user-friendly by guessing the date format of a non-ISO 8601 date and including a link to results using that guessed date.
"Sorry, "3/24/15" is not a valid date. The expected date format is "YYYY-MM-DD". Example: "2015-07-02". Did you mean: 2014-03-24"
Fortunately, Wikipedia has a list of common date formats used in the world.