Add Default MySQL Limits to Schema

[esoterik]

Discovered in #1501. Rails 4.2 adds field limits from the database to the schema when running migrations; we should make this change to the schema by running rake db:migrate on master.

[esoterik]

Here's the relevant rails issue: rails/rails#19001

[zeffman]

Do we want better error handling? When you go over the limit the site throws the "We're sorry, but something went wrong. We've been notified about this issue and we'll take a look at it shortly" notification. We could go back and add validation to all the fields--not sure if that's worth it.

[orenyk]

Good point, we'll open up a new issue to handle cases like this.