Dev Install: Add support for --yes option to assume y's to all prompts.

Also some fixes to gmerge workflow to allow easy integration testing.

BUG=chromium-os:12388, chromium-os:37901
TEST=Ran it with devmode-test

Change-Id: If511a65fb81fb2ed3d425005490efc9353283274
Reviewed-on: https://gerrit.chromium.org/gerrit/44763
Commit-Queue: Chris Sosa <sosa@chromium.org>
Reviewed-by: Chris Sosa <sosa@chromium.org>
Tested-by: Chris Sosa <sosa@chromium.org>
3 files changed