#217 Added error handlers for school.

The issues that arose with this was that the field for spanish speaking delegates wasn't returning an error as a required field, so I removed the default values in the model and adjusted the unit tests so that there were required. Also I didn't handle errors for the country field because when you switch between international or USA the country state variable doesn't get reset to an empty string. I'm pretty sure making that fix is in another task, or I can open up a new diff to handle that as soon as this one is good.
Style nit: two nested `if` statements can just as easily be written with `&&`:

```javascript
if (this.state.errors.school &&
    this.state.errors.school[0][field]) {
  // Do stuff...
}
```

I'll merge this and correct it to save you the trouble.