RFR 9: 8066750 Remove HTTP proxy implementation and tests from RMI

The RMI http proxy mechanism was deprecated in Java SE 8. Please review the removal of now dead code for the RMI Http proxy implementation and tests. Webrev: http://cr.openjdk.java.net/~rriggs/webrev-httpproxy-8066750/ Issue: https://bugs.openjdk.java.net/browse/JDK-8066750 Thanks, Roger