Update autoroller to use Gerrit.
Update autoroller to use Gerrit.

Rietveld has been having problems since the migration.

NOTRY=True

Bug: chromium:738330
Change-Id: I54538eee9f5734fac731702fb592580afcae3fae
Reviewed-on: https://webrtc-review.googlesource.com/1231
Reviewed-by: Patrik Höglund <b486136ee68458b09c92c86c39f451c87d6ef6a1@webrtc.org>
Commit-Queue: Edward Lemur <d05609f027dc667cc37492b1dc1bdea5d60fa82a@webrtc.org>
Cr-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#19834}
TimothyGu/libilbc,ShiftMediaProject/libilbc,TimothyGu/libilbc,ShiftMediaProject/libilbc,TimothyGu/libilbc,TimothyGu/libilbc,ShiftMediaProject/libilbc,ShiftMediaProject/libilbc,ShiftMediaProject/libilbc,TimothyGu/libilbc