explicitly require jquery (rather than using global $)

test plan:
 * set a global javascript include (in account settings)
   (e.g. //code.jquery.com/jquery-1.11.0.min.js)
 * navigating through draft-state wiki pages should all work

Change-Id: I4823e336986ee1eb7a09aa9da3db0068314f62ee
Reviewed-on: https://gerrit.instructure.com/30459
Tested-by: Jenkins <jenkins@instructure.com>
Reviewed-by: Jeremy Stanley <jeremy@instructure.com>
Product-Review: Jeremy Stanley <jeremy@instructure.com>
Reviewed-by: Ryan Shaw <ryan@instructure.com>
QA-Review: Matt Fairbourn <mfairbourn@instructure.com>