some refactoring

common/step.go

@@ -0,0 +1,17 @@
+package common
+
+// A step represents a step in the build process, including
+// the execution environment and parameters.
+type Step struct {
+	Name        string
+	Image       string
+	Environment []string
+	Volumes     []string
+	Hostname    string
+	Privileged  bool
+	Net         string
+
+	// Config represents the unique configuration details
+	// for each plugin.
+	Config map[string]interface{} `yaml:"config,inline"`
+}