Fix BigBingo conversions so it will work on iPads.

Summary: See D11988

Test Plan: See D11988

Reviewers: eater, alpert

Reviewed By: alpert

Subscribers: aria, #data-science

Differential Revision: http://phabricator.khanacademy.org/D12218
Ensure that it takes more than 0 minutes to paint a wall

Reviewers: eater

Reviewed By: eater

Differential Revision: http://phabricator.khanacademy.org/D12135
Ensure points always on graph

Reviewers: eater

Reviewed By: eater

Differential Revision: http://phabricator.khanacademy.org/D12245
Add units to solution box

Reviewers: eater

Reviewed By: eater

Differential Revision: http://phabricator.khanacademy.org/D11743
Fix interface.js so it only marks conversions in BigBingo when it can.

Summary:
See D12218

typeof returns a string, so respect that.

Test Plan: See D12218

Reviewers: alpert, aria

Subscribers: eater

Differential Revision: http://phabricator.khanacademy.org/D12321