* Make this demo support GPU

Change float to real in NormLayer.h

add rnn_cn.md

Fix data provider bug in srl demo

Fix typo in PyDataProvider2.py

Add const to GradientMachine::eval

Adding namespace in timing macros

Once encoutering a single sample whose size is larger than batch size,
the provider will yield empty batch and terminate the current pass unexpectedly
if can_over_batch_size=False.

priorbox layer for Single Shot Multibox Detection Network

* hidden decorator kwargs in DataProvider.__init__
* also add unit test for this.

Support user specified label input in tests

Remove not used params in GradientMachine::start

Fix bug in config_parse.py when batch_norm layer is used in RecurrentLayerGroup

* hidden decorator kwargs in DataProvider.__init__
* also add unit test for this.