Add cryptographic libraries/tools

[vixentael]

I found your list after reading slides. I thought it would be useful to add some tools that developers can use to make their applications more secure (and to encrypt their users data from prying eyes!).

I've added Themis and Acra, both projects written by cryptographers for applied developers, both are open source and free to use. (Disclaimer: I'm a maintainer for both of them.)

Themis is a library, especially useful for building encrypted communication for multi-platform applications (for example, mobile apps with server-side written in Python).

Acra is a more complex encryption tool for databases. Acra allows to selectively encrypt sensitive records with strong multi-layer cryptography in client-side application. Client-side app doesn't have decryption key, thus compromising app won't lead to stealing key and decrypting data in the database. Acra has client libraries written in Python.