Portainer: Add the ability to add host file entries when creating/updating a service

Host network is not available at the moment for Swarm services (this is a Docker limitation).

It should be available in Docker 17.06 version (not released yet), see: https://github.com/moby/moby/pull/32981

Portainer should automatically load and display that network when using 17.06, please re-open if you have issues once the version is out.

in 17.05 docker service create can use --host mysqlhost:10.0.0.2 to add mysqlhost to /etc/hosts，17.05 is released

Ah indeed, you're looking at adding Host file entries (like in the container-creation view). Sorry, I'll tag this as an enhancement then.