Enable user defined port and proto for metrics http listener

[matthsmi]

Currently port is statically set to :8080. That doesn't work for everyone.

Make it so that in the globals you can specify the the listening port, and the protocol.
If it's http, should be simple. If it's https, then require some tls bits.

[matthsmi]

Done a few things here.

• added the http-proto / http-port / http-tls-cert / http-tls-key [global] configuration options.
• tweaked the monitor listener to bind to either non tls or tls ports based upon aforementioned configuration options.
• added some tests against that change
• updated base docker image to alpine3.8 and golang 1.11.0
• shuffled some stuff around (eg: alog/ -> internal/alog/ , stats/ -> internal/stats/). Hoping to do some more cleanup of that soon.
• updated it all so building/testing works again.