Add development feature flag for student planner
Add development feature flag for student planner

closes FALCOR-174

Test Plan:
  - Feature flag shows up on the feature flag screen

Change-Id: I497d56f92961103f5affd1df6af3eef935fdcf6d
Reviewed-on: https://gerrit.instructure.com/105309
Reviewed-by: Ed Schiebel <0ca8a83847a5889cf05cb219c0ab09f6b646243b@instructure.com>
QA-Review: Dan Sasaki
Tested-by: Jenkins
Product-Review: Clay Diffrient <9dff2e5c98626d20d2848250c411e8009465bb87@instructure.com>

venturehive/canvas-lms,djbender/canvas-lms,sfu/canvas-lms,djbender/canvas-lms,instructure/canvas-lms,sfu/canvas-lms,sfu/canvas-lms,djbender/canvas-lms,sfu/canvas-lms,djbender/canvas-lms,instructure/canvas-lms,venturehive/canvas-lms,venturehive/canvas-lms,instructure/canvas-lms,instructure/canvas-lms,venturehive/canvas-lms,sfu/canvas-lms,instructure/canvas-lms,sfu/canvas-lms,sfu/canvas-lms,instructure/canvas-lms,instructure/canvas-lms