Hashing API

Here is the Hashing API I have written as part of my GSoC project. Also added a  check of policy files for JCE in JCELoader. 
@bertm said that I should include this in the docs. And the official java docs use this same phrase for MessageDigest.isEqual(): http://docs.oracle.com/javase/7/docs/api/java/security/MessageDigest.html#isEqual(byte[],%20byte[])