[Ach] HTTP Public Key Pinning (HPKP), added new theory section and updated Apache-Config. #113

[Gunnar Haslinger]

I added a new theory section in SSL covering HTTP Public Key Pinning (HPKP)
plus added the corresponding Apache-Config.

https://github.com/BetterCrypto/Applied-Crypto-Hardening/pull/113

Feedback is welcome.

(It's my first contribution to the BetterCrypto-Guide and I'm not so
fluent in LaTex, hopefully it matches your coding-guidelines).

regards,
Gunnar