Adds HttpRequestMatcher interface.
Add DefaultHttpRequestMatcher that matches request using equals method.
Add HttpRequestMatcher which matches requests even if they have extra http header entries.
Extend HttpResponseProvider with method to add HttpRequestMatcher.

Also adapt classes that implement HttpResponseProvider.
Add additional test that proves using a custom matcher works as expected.
Version bump to 3.0: HttpResponseProvider interface has additional method added.
Add version 3.0 change log.