Add support for CTS mode

Addresses https://github.com/intel-hadoop/diceros/issues/2

OpenSSL's AES does not support CTS mode. Instead, I have borrowed JDK 7's CipherTextStealing.java and modified it to fit into Diceros. I see the same performance benefit with Diceros AES CTS as with Diceros AES CBC, which is expected.

I have not done correctness checking beyond adding CTS mode to the unit test framework. See https://github.com/intel-hadoop/diceros/issues/3 for followup.