Squashed commit of the following:
Squashed commit of the following:

commit b52273baaa13ea000cf904b4ea4e215410bca908
Merge: 8149625 48c0e9e
Author: Romain Thouvenin <romain.thouvenin@gmail.com>
Date:   Sun Jan 31 09:01:47 2016 +0100

    Merge branch 'master' into notmnist-lowmem

commit 81496253f4b2511cf2bbc72125a12bc8240f7565
Author: rthouvenin <romain.thouvenin@gmail.com>
Date:   Sat Jan 30 10:39:02 2016 +0100

    Load dataset classes separately to require less memory

tensorflow/examples,tensorflow/examples,tensorflow/examples,tensorflow/examples,tensorflow/examples,tensorflow/examples,tensorflow/examples,tensorflow/examples,tensorflow/examples