#377 fix the issue in matchDomain method

Let's say in the Cookie object, the cookie domain is google.com, if the matching domain is www.google.com, it should be matched. But currently in the code this domain won't be matched.
Please refer to the RFC document http://tools.ietf.org/html/rfc6265#section-5.1.3
Now in this fix matchDomain method should work exactly as described in rfc 6265