Go read /etc/hosts with net.lookupStaticHost()

[michalmatczuk]

https://github.com/saucelabs/forwarder/commit/0b35f78a396959079fdb475aa16106ec16f09807

[michalmatczuk]

We need to check if given domain name points to localhost.

Previously we used resolver with custom dialer that never dials connection but this resulted in unexpected allocations :/

This patch links net.lookupStaticHost(), clean and simple.