Issue #25 Added method to obtain last modified date to Resource
Issue #25 Added processing of If-Modified-Since header
Issue #25 Fixed compile error in HttpResponseTest
Issue #25 Implemented test for checking If-Modified-Since header
Merge branch 'master' into 25

Conflicts:
	s3auth-hosts/src/test/java/com/s3auth/hosts/DefaultResourceTest.java
Issue #25 Added Apache HttpClient dependency to s3auth-relay pom.xml
Merge pull request #93 from carlosmiranda/25

#93: pull request Issue #25 If-Modified-Since header is now being processed