revert appveyor skips as windows builds are pretty unstable
revert appveyor skips as windows builds are pretty unstable

mkuzmin/packer,timsutton/packer,hashicorp/packer,youhong316/packer,pecigonzalo/packer,ricardclau/packer,grubernaut/packer,ricardclau/packer,bryson/packer,grubernaut/packer,rnaveiras/packer,paulmey/packer,paulmey/packer,tb3088/packer,tb3088/packer,youhong316/packer,dave2/packer,dave2/packer,tas50/packer,rnaveiras/packer,tas50/packer,tb3088/packer,tas50/packer,bryson/packer,timsutton/packer,mkuzmin/packer,tb3088/packer,rnaveiras/packer,paulmey/packer,youhong316/packer,bryson/packer,dave2/packer,ricardclau/packer,paulmey/packer,timsutton/packer,bryson/packer,youhong316/packer,paulmey/packer,mkuzmin/packer,mitchellh/packer,rnaveiras/packer,pecigonzalo/packer,grubernaut/packer,bryson/packer,mkuzmin/packer,rnaveiras/packer,tas50/packer,paulmey/packer,pecigonzalo/packer,mitchellh/packer,bryson/packer,hashicorp/packer,ricardclau/packer,tb3088/packer,ricardclau/packer,youhong316/packer,dave2/packer,dave2/packer,dave2/packer,rnaveiras/packer,mitchellh/packer,grubernaut/packer,mkuzmin/packer,mitchellh/packer,hashicorp/packer,tas50/packer,timsutton/packer,hashicorp/packer,tb3088/packer,ricardclau/packer,timsutton/packer,grubernaut/packer,youhong316/packer,timsutton/packer,pecigonzalo/packer,mkuzmin/packer,mitchellh/packer,grubernaut/packer,tas50/packer