added strategy pattern sample

strategy/src/main/java/com/iluwatar/SpellStrategy.java

@@ -0,0 +1,10 @@
+package com.iluwatar;
+
+public class SpellStrategy implements DragonSlayingStrategy {
+
+	@Override
+	public void execute() {
+		System.out.println("You cast the spell of disintegration and the dragon vaporizes in a pile of dust!");
+	}
+
+}