add test-watch npm script
add test-watch npm script

goes really well with the jspec script

test plan:
- builds pass

Change-Id: If596d5f1983957eb9862021b8abaaf8f80c747c1
Reviewed-on: https://gerrit.instructure.com/96454
Tested-by: Jenkins
Reviewed-by: Steven Burnett <a0b450117c5d20a22d5c4d52bb8ae13adee003d8@instructure.com>
Product-Review: Felix Milea-Ciobanu <9384aa226ac9d3237ed0bc52e18ffcb251ee0bf7@instructure.com>
QA-Review: Felix Milea-Ciobanu <9384aa226ac9d3237ed0bc52e18ffcb251ee0bf7@instructure.com>

instructure/canvas-lms,sfu/canvas-lms,sfu/canvas-lms,venturehive/canvas-lms,instructure/canvas-lms,sfu/canvas-lms,matematikk-mooc/canvas-lms,venturehive/canvas-lms,sfu/canvas-lms,grahamb/canvas-lms,djbender/canvas-lms,SwinburneOnline/canvas-lms,grahamb/canvas-lms,venturehive/canvas-lms,instructure/canvas-lms,instructure/canvas-lms,grahamb/canvas-lms,sfu/canvas-lms,matematikk-mooc/canvas-lms,djbender/canvas-lms,instructure/canvas-lms,SwinburneOnline/canvas-lms,instructure/canvas-lms,instructure/canvas-lms,matematikk-mooc/canvas-lms,SwinburneOnline/canvas-lms,matematikk-mooc/canvas-lms,sfu/canvas-lms,grahamb/canvas-lms,grahamb/canvas-lms,sfu/canvas-lms,djbender/canvas-lms,djbender/canvas-lms,venturehive/canvas-lms,SwinburneOnline/canvas-lms