Configuration file parsing problem, if batch_norm_layer connected to fc_layer.

The config is like:
```
fc = fc_layer(input=pool, size=256)
out = batch_norm_layer(input=fc)
```
The error is:
```
Input layer __fc_layer_0__: Incorrect input image size 4 * 4 for input image pixels 1
```
The error occurred on https://github.com/PaddlePaddle/Paddle/blob/develop/python/paddle/trainer/config_parser.py#L1162
