Added header handling for RegexSelectors and UriTemplateSelectors. Added a method to the Selector interface that exposes a setHeader(Selector, Event) method that will extract any header values from the Selector being matched against and set those values as headers on the Event. Also added the setting of headers into the dispatcher implementations which is unfortunately the only place where the left-hand side of the Selector comparison, the right-hand side, and the Event are all in the same place. This doesn't seem to impact the performance of standard Selectors because they skip over setting headers, but for UriTemplate and Regex Selectors, it will probably impact performance, the amount of which is not yet determined.