#136 Support for Severity Observable

[egucciar]

Hello,

I implemented Severity as per some suggestions in this ticket:

https://github.com/Knockout-Contrib/Knockout-Validation/issues/136

I don't think this pull request is ready to merge, we need to squash and write tests. I'm just not too savy on writing tests with Qunit, so I was wondering if someone could give some direction?

How many tests do I need to write?

Also willing to discuss changes to the proposed code.

Thanks, Erica