Support of HTTPCrypt in the Web interface

by Manish Malik for Rspamd spam filtering system

Rspamd supports opportunistic encryption of all messages. However, its current web interface does not support encryption at all. So in this project I will be using tweetnacl-js after modifying it in accordance with cryptobox used in rspamd for encrypting the HTTP session of its web interface and hence improving its security. Also making it resilient against some MiTM attacks such as replay attack.