Events listener using Predicate selectors instead of cssSelectors

Relates to https://github.com/ArcBees/gwtquery/issues/177 and https://github.com/ArcBees/gwtquery/pull/302.

I add this strategy to avoid the performance problem issue-177, although I end up using the alternative solution pull-302.

Anyway, this path might be useful for some situations where the user want a programmatic filtering on event listeners.