Added OAuth token management SPI

git-svn-id: https://svn.apache.org/repos/asf/wookie/trunk@1566436 13f79535-47bb-0310-9956-ffa450edef68
Updated OAuth client to use SPI

git-svn-id: https://svn.apache.org/repos/asf/wookie/trunk@1566438 13f79535-47bb-0310-9956-ffa450edef68