add tests files to everything to test compilation

command/validate/command_test.go

+package validate
+
+import (
+	"github.com/mitchellh/packer/packer"
+	"testing"
+)
+
+func TestCommand_Impl(t *testing.T) {
+	var raw interface{}
+	raw = new(Command)
+	if _, ok := raw.(packer.Command); !ok {
+		t.Fatalf("must be a Command")
+	}
+}

packer_test.go

+package main

plugin/builder-amazon-ebs/main_test.go

+package main

plugin/builder-amazon-instance/main_test.go

+package main

plugin/builder-digitalocean/main_test.go

+package main

plugin/builder-virtualbox/main_test.go

+package main

plugin/builder-vmware/main_test.go

+package main

plugin/command-build/main_test.go

+package main

plugin/command-fix/main_test.go

+package main

plugin/command-validate/main_test.go

+package main

plugin/post-processor-vagrant/main_test.go

+package main

plugin/provisioner-file/main_test.go

+package main

plugin/provisioner-shell/main_test.go

+package main