extend lazy list to set dataType option for requests

Comparisons to ENV.current_user_id (string) to users[0].id (int)
were failing. I made the api return string ids so it would all work
properly

Fixes CNVS-15484

Test Plan:

Setup -
1. Have a test course with 5 or so students and a teacher.
2. Log into test course as teacher.
3. [People]
4. [+ Group Set]
5. Give name, check 'allow self sign-up', create '3' groups now
6. Assign students to each group.

1. Log in as a student that is assigned to a group.
2. Go to test course.
3. [People]
4. [Groups]
5. "Leave" and "Switch To" should be displayed rather than join

Change-Id: I7129ae49ad3cd6e2871b5f0bc8d92db533a710b3
Reviewed-on: https://gerrit.instructure.com/43126
Tested-by: Jenkins <jenkins@instructure.com>
Reviewed-by: Alex Boyd <aboyd@instructure.com>
Reviewed-by: Braden Anderson <braden@instructure.com>
QA-Review: Trevor deHaan <tdehaan@instructure.com>
Product-Review: Braden Anderson <braden@instructure.com>