Nitishm/bug/409/custom reverse workflow crash (#410)

* Custom executor example

Signed-off-by: Nitish Malhotra <nitish.malhotra@gmail.com>

* Instantiate CustomReverse executor with the image instance

Signed-off-by: Nitish Malhotra <nitish.malhotra@gmail.com>

pkg/executor/custom.go

@@ -16,7 +16,7 @@ type CustomForward struct {
 }
 
 func (exec CustomForward) Reverse() Executor {
-	return CustomReverse{}
+	return CustomReverse{exec.Image}
 }
 
 func (exec CustomForward) GetName() string {
@@ -36,7 +36,7 @@ type CustomReverse struct {
 }
 
 func (exec CustomReverse) Reverse() Executor {
-	return CustomForward{}
+	return CustomForward{exec.Image}
 }
 
 func (exec CustomReverse) GetName() string {