Small change to SEF for debugging

Kevin, 

I am wanting you to try this version of SEF so you can see the difference between what I get with 2 different types of errors. 

One type is when I clear out active field when editing a country. That is sending a good error message that I can handle. 

The 2nd type is when I change the url on country collection to "countrya" or something else wrong. That error is different, and cannot be retrieved from resp.exception. Instead the error message is in xhr.responseText. I cannot get at the error message (not showing as JSON) unless I do some javascript parsing. 

I put 2 console log messages in backbone.sef.js so you can see what I'm talking about. 

We can talk about it tomorrow. 

~ lisa