Numerical questions accept flexible ranges

The back-end will now accept answer ranges in a more flexible manner, so
providing a range of [50,10] or [-3,-8] will work.

Closes CNVS-11282

TEST PLAN
---- ----

  - create a quiz with a numerical question:
    - choose "answer in range" for an answer type
    - play with something similar to the combinations listed below and
      verify that you get the proper results
  - answer the quiz question by the student every-time you try a new
    combination and verify the grading is correct

Combinations:

  - from: -5, to: 10, answer: 7 (correct)
  - from: 10, to: -5, answer: 7, or 0, or -3 (correct)
  - from: -2.5, to: -3.5, answer: -3 (correct)
  - from: -3.5, to: -2.5, answer: 3 (incorrect)

Or just use your imagination :) The point is, the ranges should be
accepted and work properly regardless of if you specify the smaller
number first (this was an issue for negative ranges)

Change-Id: I3c3f8638f8244d6417effeec4b4f0e29198ea845
Reviewed-on: https://gerrit.instructure.com/32935
Tested-by: Jenkins <jenkins@instructure.com>
Reviewed-by: Jason Madsen <jmadsen@instructure.com>
QA-Review: Caleb Guanzon <cguanzon@instructure.com>
Product-Review: Derek DeVries <ddevries@instructure.com>