move twitter to gem

fixes: CNVS-12492

test-plan:
* Test that all things Twitter related still work

Change-Id: Ib656c5bfcb2dc8490a6fa6f214b0f6dce25ad181
Reviewed-on: https://gerrit.instructure.com/33193
Tested-by: Jenkins <jenkins@instructure.com>
QA-Review: Trevor deHaan <tdehaan@instructure.com>
Reviewed-by: Mike Nomitch <mnomitch@instructure.com>
Reviewed-by: Liz Abinante <labinante@instructure.com>
Product-Review: Simon Williams <simon@instructure.com>