Added save_records to push monitor function and updated implementation of RNNs

Added save_records to push monitor function:
Initialize {batch, val, example, epoch, time} records of new monitor channels with those of old monitor channels in order to preserve and pass the training information, when re-training from the checkpoint. Now, it can be much easier to plot the whole curves. A user can use this functionality by setting save_records flag of push_monitor function into 1. 

Updated implementation of RNNs:
1. One could choose to use or not use the masks.
2. LSTM implementation has changed
3. included add_noise function which adds Gaussian noise to parameters
4. Recurrent weights are always orthogonally initialized using scipy.linalg.orth()


Actually, `add_channel` does not know whether we are reloading or setting the channels for the first time.
I think we could make add a member of Monitor instead, for instance `Monitor.on_channel_conflict`, that would default to "error", but could be "copy_history" or "overwrite". Then, `push_monitor_` would change the value of that member to "copy_history".