Added Test dependencies to project

Updated to jQuery 1.9 and the latest versions of QUnit and SinonJS.  Had to modify the logic in addFromDom() to ensure that a string is returned for the template (previously jQuery would return null, now it returns undefined).
Fixed Issue #16 - changed addFromDom() selector logic.

Thanks @pinterface for the original issue; instead of passing a selector string to jQuery, we're now using document.getElementById which avoids any issues with "special" characters in the template's id attribute.

Added new test assertion method to ensure that a given jQuery Mustache instance contains a collection of templates.