Upgraded project version to 4.4-alpha1-SNAPSHOT; upgraded minimal Java level to 1.6; re-enabled win atuh module

git-svn-id: https://svn.apache.org/repos/asf/httpcomponents/httpclient/trunk@1561061 13f79535-47bb-0310-9956-ffa450edef68
Added missing @Override annotations

git-svn-id: https://svn.apache.org/repos/asf/httpcomponents/httpclient/trunk@1561063 13f79535-47bb-0310-9956-ffa450edef68
Use Java 1.6 String#isEmpty(); minor cleanups

git-svn-id: https://svn.apache.org/repos/asf/httpcomponents/httpclient/trunk@1561064 13f79535-47bb-0310-9956-ffa450edef68
Use String methods and constructors that require Charset instead of String

git-svn-id: https://svn.apache.org/repos/asf/httpcomponents/httpclient/trunk@1561066 13f79535-47bb-0310-9956-ffa450edef68
Updated @since tag for Win Auth classes

git-svn-id: https://svn.apache.org/repos/asf/httpcomponents/httpclient/trunk@1561068 13f79535-47bb-0310-9956-ffa450edef68