breeze.directives: improved z-append-to handling of ng-repeat

[mcshaz]

When using bootstrap input groups, the z-append-to allows a query selector to identify an element to append the z-decorator to.

However, within an ng-repeat it is a pain to generate unique ids to append to. The accompanying pull request will append to an element in exactly the same way if a single DOM element matches the querySelector, but if more than one element matches, it will find the first matching ancestor of the input/tetxarea/select element being validated. In this way the z-append-to directive now works with class and element selectors.