Port to Python 3

[In Progress]
I am really excited that coding period has started for GSOC 2018. All weeks progress will be logged here.

WEEK 1
I was busy with my University finals, but managed to start the project coding last week. I worked on porting nutrition activity for Sugar Labs. Moreover progress can be found at https://github.com/sugarlabs/nutrition/pull/4

I could not test with sugar-toolkit-gtk3 because of exams and hence it has some bugs to fix. Thanks to Mr. James Cameron, Mr. Walter Cameron and Mr. Rahul Bothra for the update.
Task for this week - Fix it as soon as possible.
Task for next week - I am planning to start with finance activity for next week porting and speed up the work so that more and more activities can be ported during GSOC.
Update for this week - There is some package incompatibilty with Ubuntu Bionic like libtool-2.0 is required and upstream has already shifted to libtool-2.2 so its giving error at installation with toolkit standalone, Maybe there will be time when repositories will require a maintaince to keep up with the upstreams.