Allow configuring SSL certificate to REMS

[Macroz]

Allow configuring SSL certificate to REMS, so there doesn't need to be a an SSL proxy, and the connection can be secure all the way in.

• setting SSL port, keystore and password through config options

[Macroz]

Here are the relevant configs.

NB: The keystore file path is relative to the working directory so an absolute path is perhaps the safe way to go.

 ;; HTTP server port.
 :port 3000 ; can be set to nil if only SSL is used

 ;; SSL configuration, if SSL is not terminated before
 :ssl-port nil ; no SSL by default
 :ssl-keystore nil ; Java keystore file
 :ssl-keystore-password nil ; (optional) password of key file