ericmbarnard/Knockout-Validation — pull request #16 by michalporeba (2012-01-30 14:39:33+00:00)
Title: new validators

This commit adds three new validators
* `equal` - can be used to enforce user confirming something with checkbox or to compare two password boxes
* `notEqual` - can be used to force user to select option from a dropdown or to enforce. could be also used to make sure to fields (phone numbers for instance) are different
* `unique` - checks if the value is unique within a collection

additionally I have changed `email` validator to accept empty string as I think that if email is really mandatory then it should be explicitly said with `required` validator. It will also result in more user friendly messages.

I have added `getValue()` to utils that is similar to ko.utils.unwrapObservable but works on any function.
I then used it to allow validation parameters to be passed as object, function, observable or function returning an observable. It allows to build more complex validation rules.