修改抛出的异常信息，把memecached改为redis，代码135行和167行 (apache#242)

Author: ghsy158

dubbo-rpc/dubbo-rpc-redis/src/main/java/com/alibaba/dubbo/rpc/protocol/redis/RedisProtocol.java

@@ -132,7 +132,7 @@ protected Result doInvoke(Invocation invocation) throws Throwable {
                         }
                     }
                     catch (Throwable t) {
-                        RpcException re = new RpcException("Failed to invoke memecached service method. interface: " + type.getName() + ", method: " + invocation.getMethodName() + ", url: " + url + ", cause: " + t.getMessage(), t);
+                        RpcException re = new RpcException("Failed to invoke redis service method. interface: " + type.getName() + ", method: " + invocation.getMethodName() + ", url: " + url + ", cause: " + t.getMessage(), t);
                         if (t instanceof TimeoutException || t instanceof SocketTimeoutException) {
                             re.setCode(RpcException.TIMEOUT_EXCEPTION);
                         } else if (t instanceof JedisConnectionException || t instanceof IOException) {
@@ -164,7 +164,7 @@ public void destroy() {
                 }
             };
         } catch (Throwable t) {
-            throw new RpcException("Failed to refer memecached service. interface: " + type.getName() + ", url: " + url + ", cause: " + t.getMessage(), t);
+            throw new RpcException("Failed to refer redis service. interface: " + type.getName() + ", url: " + url + ", cause: " + t.getMessage(), t);
         }
     }