Change Graph Settings to RangeInput

Summary: Just abstracts it a little, makes it nicer to read

Test Plan:
Open up interactive-graph, try changing the
(1) x range
(2) y range
(3) tick step
(4) grid step
(5) snap step

Reviewers: jack

Reviewed By: jack

Subscribers: alpert

Differential Revision: http://phabricator.khanacademy.org/D7521