Adding GDH project to Java list (#55)

* Adding GDH project to Java list

* Add GDH project to Java list

README.md

@@ -253,6 +253,7 @@ A curated list of cryptography resources and links.
 - [Apache Shiro](http://shiro.apache.org/) - Performs authentication, authorization, cryptography and session management.
 - [Bouncy Castle](https://www.bouncycastle.org/java.html) - All-purpose cryptographic library. JCA provider, wide range of functions from basic helpers to PGP/SMIME operations.
 - [Flexiprovider](http://www.flexiprovider.de/) - Powerful toolkit for the Java Cryptography Architecture.
+- [GDH](https://github.com/maxamel/GDH) - Generalized Diffie-Hellman key exchange Java library for multiple parties built on top of the Vert.x framework.
 - [Google Keyczar](https://github.com/google/keyczar) - Easy to use, yet safe encryption framework with key versioning.
 - [Google Tink](https://github.com/google/tink) - A small crypto library that provides a safe, simple, agile and fast way to accomplish some common crypto tasks.
 - [Java Themis](https://github.com/cossacklabs/themis/wiki/Java-and-Android-Howto) - Java/Android wrapper on Themis. High level crypto library for storing data (AES), secure messaging (ECC + ECDSA / RSA + PSS + PKCS#7) and session-oriented, forward secrecy data exchange (ECDH key agreement, ECC & AES encryption).