Enabled use of multiple matcher groups in http header checks, close #207...

...4

checks on multiple matcher groups can now be done like this:
           new HttpHeaderRegexCheckBuilder[(String, String)](HttpHeaderNames.SetCookie, "COOKIE_NAME=.*; Version=(\\d+); HttpOnly; Max-Age=(\\d+); Expires=.*").findAll.is(Seq(("1","1800")))