Removed reference to deprecated Assert

git-svn-id: https://svn.apache.org/repos/asf/httpcomponents/httpclient/trunk@1575901 13f79535-47bb-0310-9956-ffa450edef68
HTTPCLIENT-1479: fixed NPE in RequestAuthCache caused by incorrect context initialization

git-svn-id: https://svn.apache.org/repos/asf/httpcomponents/httpclient/trunk@1575902 13f79535-47bb-0310-9956-ffa450edef68