Fix AppVeyor builds (#2289)
Fix AppVeyor builds (#2289)

* Attempting to fix AppVeyor builds

* Trying again, 2015 image this time

* Use Appveyor's Go 1.11 stack

* Restore GOPATH\bin to PATH and delete old image config

* Add gcc to path manually

joshix/caddy,joshix/caddy,joshix/caddy