Add blackbox optimizers and secondorder blackbox optimizers (#249)

This is a port of the work by: Krzysztof Choromanski, Mark Rowland,
Vikas Sindhwani, Richard E. Turner, Adrian Weller:  "Structured Evolution
with Compact Architectures for Scalable Policy Optimization",
https://arxiv.org/abs/1804.02395

Author: salaast