Formatted all files to the same standard

interpreter/src/main/java/com/iluwatar/NumberExpression.java

@@ -7,11 +7,11 @@ public class NumberExpression extends Expression {
 	public NumberExpression(int number) {
 		this.number = number;
 	}
-	
+
 	public NumberExpression(String s) {
 		this.number = Integer.parseInt(s);
 	}
-	
+
 	@Override
 	public int interpret() {
 		return number;