Modified directive so that it does not create an isolate scope.

I have been using this directive with great success until I applied it to an element that had other directives applied to it and got a [multidir error](https://docs.angularjs.org/error/$compile/multidir).

Turns out that both of these directives wanted to create an isolate scope which doesn't work. So I looked into the code for the debounce directive and there really isn't a need for an isolate scope. So I modified it here to use the [$parse](https://docs.angularjs.org/api/ng/service/$parse) service to read the values off the attributes. It seems to work great and now I can combine it with other directives more easily.