Convert to nbformat 4 and support py3k and misc fixes#1

jcfr wants to merge 9 commits intoluisibanez:masterluisibanez/tensorflow_tutorial:masterfrom

jcfr:convert-to-nbformat-4-and-support-py3k-and-misc-fixesjcfr/tensorflow_tutorial:convert-to-nbformat-4-and-support-py3k-and-misc-fixesCopy head branch name to clipboard