travis-ci: allow failures on windows
travis-ci: allow failures on windows

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