Parameters for binding classes using parentheses

[drosen0]

Here's an implementation of #1 except using parentheses and commas, like:

<div data-class="renderSection(overview)"></div>

<!-- ko class: render(section,overview) -->
<!-- /ko -->

No spaces are allowed, except between classes. I believe this limitation is fine, since the intent is only to pass a string or two as an identifier. I already started using it and I like the new syntax better than the : syntax.

[rniemeyer]

Landed the implementation in #7 as opposed to this one.