Resolve #1298

* use serial.load in CIFAR10._unpickle
* remove "scripts/tutorials/grbm_smd/make_dataset.py" from pep8 whitelist
* refine serial.load for interoparability between Python 2 and 3
* remove N and np, aliases of numpy
We shouldn't erase this TODO without doing it...

The right thing to do here is get rid of CIFAR10._unpickle and change the internal calls to _unpickle to call serial.load instead.

No other dataset class, including CIFAR100, has an _unpickle method. It's just totally unnecessary and we shouldn't be spending time maintaining it.