1.6.4-pini1

Rebase on nginx-proxy/nginx-proxy 1.6.4.

Features enabled by this fork:

• Variable ENABLE_HTTP_ON_MISSING_CERT defaults to false (instead of true for upstream)
• HTTPS passthrough

Features that will be deprecated:

• multiport syntax for VIRTUAL_PORT variable
• Different ports per virtual host for the same container

Please use the new VIRTUAL_HOST_MULTIPORTS variable instead.