New AndStrategy and OrStrategy starts empty. (#231)

# Describe Request

New AndStrategy and OrStrategy starts empty.

# Change Type

New feature.

strategy/and_strategy.go

@@ -23,9 +23,9 @@ type AndStrategy struct {
 }
 
 // NewAndStrategy function initializes an empty and strategies group with the given name.
-func NewAndStrategy(name string) *AndStrategy {
+func NewAndStrategy(name string, strategies ...Strategy) *AndStrategy {
 	return &AndStrategy{
-		Strategies: []Strategy{},
+		Strategies: strategies,
 		name:       name,
 	}
 }

strategy/or_strategy.go

@@ -20,9 +20,9 @@ type OrStrategy struct {
 }
 
 // NewOrStrategy function initializes an empty or strategies group with the given name.
-func NewOrStrategy(name string) *OrStrategy {
+func NewOrStrategy(name string, strategies ...Strategy) *OrStrategy {
 	return &OrStrategy{
-		Strategies: []Strategy{},
+		Strategies: strategies,
 		name:       name,
 	}
 }