Only set remote push values for cros remotes.

In the testing of manifests, new remotes may be added (such as
git://git.kernel.org/pub/scm/linux/kernel/git for upstream kernel
testing.)  So only calculate push values for cros remotes.

Also removes the 'internal' flag from manifest projects.

BUG=chromium-os:23277
TEST=Remote trybots.

Change-Id: Ie24b0bb681bfe5a8a2936d5beab00d5573d7af64
Reviewed-on: https://gerrit.chromium.org/gerrit/31417
Reviewed-by: Brian Harring <ferringb@chromium.org>
Tested-by: Ryan Cui <rcui@chromium.org>
Reviewed-on: https://gerrit.chromium.org/gerrit/32056
Reviewed-by: David James <davidjames@chromium.org>
3 files changed