Implement new attacks

[jonasrauber]

In this issue we collect new attacks that we would like to add to Foolbox. Feel free to propose new ones and please contribute implementations for these attacks.

• SPSA attack: https://arxiv.org/pdf/1802.05666.pdf (from Implement SPSA attack #202)
• "A geometry-inspired decision-based attack" https://arxiv.org/abs/1903.10826 (from Implementing "A geometry-inspired decision-based attack" #292)
• L-infinity CW attack (from No CW attack with L_inf norm #352)

[hfeniser]

Hi, are you interested in adding Feature Adversaries (https://arxiv.org/pdf/1511.05122.pdf) to Foolbox?

[jS5t3r]

BlackBox attacks: https://github.com/SCLBD/BlackboxBench