vet fixes

Fixes the following vet reports:

builder/amazon/common/step_ami_region_copy.go:81: arg target for printf verb %s of wrong type: github.com/mitchellh/goamz/aws.Region
builder/amazon/common/step_ami_region_copy.go:93: arg target for printf verb %s of wrong type: github.com/mitchellh/goamz/aws.Region

builder/amazon/ebs/step_create_ami.go:90: arg resp.Return for printf verb %s of wrong type: bool

builder/digitalocean/builder_test.go:267: arg b.config.SSHUsername for printf verb %d of wrong type: string
builder/digitalocean/builder_test.go:300: arg b.config.RawSSHTimeout for printf verb %d of wrong type: string
builder/digitalocean/builder_test.go:341: arg b.config.RawStateTimeout for printf verb %d of wrong type: string
builder/digitalocean/builder_test.go:382: arg b.config.PrivateNetworking for printf verb %s of wrong type: bool
builder/digitalocean/builder_test.go:397: arg b.config.PrivateNetworking for printf verb %s of wrong type: bool

builder/googlecompute/step_create_instance_test.go:42: possible formatting directive in Fatal call
builder/googlecompute/step_teardown_instance_test.go:29: possible formatting directive in Fatal call
builder/googlecompute/step_teardown_instance_test.go:39: possible formatting directive in Fatal call

builder/openstack/artifact.go:44: arg a.ImageId for printf verb %d of wrong type: string

builder/parallels/iso/builder_test.go:78: arg b.config.DiskSize for printf verb %s of wrong type: uint

builder/qemu/builder_test.go:163: arg b.config.DiskSize for printf verb %s of wrong type: uint

builder/virtualbox/iso/builder_test.go:86: arg b.config.DiskSize for printf verb %s of wrong type: uint

builder/vmware/common/step_shutdown_test.go:130: missing argument for Fatalf("%s"): format reads arg 1, have only 0 args

builder/vmware/iso/builder_test.go:178: arg b.config.DiskSize for printf verb %s of wrong type: uint

common/step_create_floppy_test.go:79: possible formatting directive in Fatal call
common/step_create_floppy_test.go:89: possible formatting directive in Fatal call
common/step_create_floppy_test.go:180: possible formatting directive in Fatal call
common/step_create_floppy_test.go:190: possible formatting directive in Fatal call

communicator/ssh/communicator_test.go:88: range variable newChannel captured by func literal

packer/template_test.go:496: possible formatting directive in Fatal call
packer/template_test.go:528: possible formatting directive in Fatal call

post-processor/vagrant-cloud/client.go:81: arg resp for printf verb %s of wrong type: *net/http.Response
post-processor/vagrant-cloud/client.go:99: arg resp for printf verb %s of wrong type: *net/http.Response
post-processor/vagrant-cloud/client.go:131: arg resp for printf verb %s of wrong type: *net/http.Response
post-processor/vagrant-cloud/client.go:156: arg resp for printf verb %s of wrong type: *net/http.Response
post-processor/vagrant-cloud/client.go:175: arg resp for printf verb %s of wrong type: *net/http.Response

provisioner/puppet-masterless/provisioner.go:196: missing argument for Errorf("%d"): format reads arg 1, have only 0 args

provisioner/salt-masterless/provisioner.go:119: arg cmd for printf verb %s of wrong type: *github.com/mitchellh/packer/packer.RemoteCmd
provisioner/salt-masterless/provisioner.go:121: arg err for printf verb %d of wrong type: error
provisioner/salt-masterless/provisioner.go:142: arg err for printf verb %d of wrong type: error
provisioner/salt-masterless/provisioner.go:157: arg err for printf verb %d of wrong type: error
provisioner/salt-masterless/provisioner.go:172: arg err for printf verb %d of wrong type: error
provisioner/salt-masterless/provisioner.go:216: arg err for printf verb %d of wrong type: error