Added stepping functionality, fixed min/max validation when typing values, added Jasmine specs

We added a couple of useful features that hopefully you'd like to merge upstream:

1. When typing a value directly into the text field, the current behavior would try to ensure that the value is within the min/max parameters set. This was a problem for example if min was 5 and max was 500 ... if you try to type 100. As soon as you type "1" it would change it to a 5. We added a validationDelay option to choose how long for it to wait before validating the input after typing.

2. Added a "step" option to increment/decrement by that number.

3. Added tests for this new behavior with Jasmine.