Use GIT_COMMITTER_IDENT for user emails.
Use GIT_COMMITTER_IDENT for user emails.

This git variable is more accurate than user.email which may not
be configured or may be configured incorrectly.

BUG=chromium-os:27939
TEST=Verified pulling email correctly.

Change-Id: Iba0fc8ba1678d26275738cdfa030c545d29594b0
Reviewed-on: https://gerrit.chromium.org/gerrit/18406
Reviewed-by: David James <f231dc574bbeb62604660cbc162d1b8642a0a3af@chromium.org>
Tested-by: Ryan Cui <5ce1592d53754a87a44fc2eb7b63d5f77cf50fdb@chromium.org>
Commit-Ready: Ryan Cui <5ce1592d53754a87a44fc2eb7b63d5f77cf50fdb@chromium.org>

chadversary/chromiumos.chromite,coreos/chromite,coreos/chromite,bpsinc-native/src_third_party_chromite,zhang0137/chromite,zhang0137/chromite,bpsinc-native/src_third_party_chromite,chadversary/chromiumos.chromite,coreos/chromite,zhang0137/chromite,bpsinc-native/src_third_party_chromite