Respect boolean value for unencrypted param
Respect boolean value for unencrypted param

Without calling value_to_boolean, passing ?unencrypted=0 still gives
an unencrypted token. This change will only return an unencrypted token
if the param is truthy (and Rails.env is development, so this change
doesn't affect production).

flag = none

Test plan:
 - POST /api/v1/inst_access_tokens?unencrypted=1 (or true)
 - Expect an unencrypted token in response (these tokens are shorter in
   length than their encrypted versions)
 - Now POST with unencrypted=0 (or false)
 - Expect an encrypred token (longer than the unencrypted version)

Change-Id: I8cccb0833789f7db0da2224048830a88751fa551
Reviewed-on: https://gerrit.instructure.com/c/canvas-lms/+/305953
Tested-by: Service Cloud Jenkins <9144042a601061f88f1e1d7a1753ea3e2972119d@instructure.com>
Reviewed-by: Davis Hyer <60fbffed049dcae9186e63e354cbc0b825bf5523@instructure.com>
QA-Review: Davis Hyer <60fbffed049dcae9186e63e354cbc0b825bf5523@instructure.com>
Product-Review: Davis Hyer <60fbffed049dcae9186e63e354cbc0b825bf5523@instructure.com>

instructure/canvas-lms,instructure/canvas-lms,instructure/canvas-lms,instructure/canvas-lms,instructure/canvas-lms,instructure/canvas-lms,instructure/canvas-lms