DATACMNS-100 - Removed Number from the Set of simple types.

Removing Number from SimpleTypeHolder's default Set of types results in
Number sub-types not explicitly listed not being considered as simple
by default.

spring-data-commons-core/src/main/java/org/springframework/data/mapping/model/SimpleTypeHolder.java

@@ -61,7 +61,6 @@ public class SimpleTypeHolder {
 		DEFAULTS.add(Date.class);
 		DEFAULTS.add(Locale.class);
 		DEFAULTS.add(Class.class);
-		DEFAULTS.add(Number.class);
 		DEFAULTS.add(Enum.class);
 	}