The JRE (since Java 6) ships with a perfectly good Base64 Encoder/Decoder. Use it.

git-svn-id: https://svn.apache.org/repos/asf/tomcat/tc7.0.x/trunk@1458742 13f79535-47bb-0310-9956-ffa450edef68
Replace Tomcat's own base64 encoder with the one from the JRE.
Deprecate Tomcat's encoder which will be removed in Tomcat 8.

git-svn-id: https://svn.apache.org/repos/asf/tomcat/tc7.0.x/trunk@1458748 13f79535-47bb-0310-9956-ffa450edef68