Native CSPRNG Support and OpenSSL Deprecation

This release adds support for the native CSPRNG functions included in PHP 7. This allows for an easier installation process due to less dependency on extensions while providing a more secure alternative to other CSPRNG implementations.

Also, due to discoveries in the insecurities of OpenSSL and known abandonment of Mcrypt, this release deprecates support for both the OpenSSL and Mcrypt random byte generators.