SEC-1054: Add method "clear" to interface AclCache. As requested.

acl/src/main/java/org/springframework/security/acls/jdbc/AclCache.java

@@ -39,4 +39,6 @@ public interface AclCache {
     MutableAcl getFromCache(Serializable pk);
 
     void putInCache(MutableAcl acl);
+
+    void clearCache();
 }

acl/src/main/java/org/springframework/security/acls/jdbc/EhCacheBasedAclCache.java

@@ -137,4 +137,8 @@ public class EhCacheBasedAclCache implements AclCache {
         }
         return value;
     }
+
+    public void clearCache() {
+        cache.removeAll();
+    }
 }