Update reporting to gather more information.

Changes:

1. Adding some code in the `done` function that tells GA if there was an error in the submission. This is a helpful custom event in Optimizely. For the next experiment, we can setup a goal for `seo-form validation error` and see which variation reduces conversions on this custom even (i.e. which variation lowers the error rate).

2. Changes the label on the global validationError function to an indicator of whether or not the field had any text entered into it. This gives us a little more insight into why the error occurred.

3. Add a value to the validationError custom event that specifies how many characters the input had inside of it. This will give us a little more insight into what the problem was.
@kylerush don't forget to trim this bad boy