lorgnette: Lots of cleanup; add scan options

Take scan options; add DBus error reporting for most failures.

BUG=chromium:239087
TEST=dbus-send of scan command with various invalid options

Change-Id: Iad3d228b4bc00ea52c38df3b22b4d922579b5c6b
Reviewed-on: https://gerrit.chromium.org/gerrit/56312
Reviewed-by: mukesh agrawal <quiche@chromium.org>
Tested-by: Paul Stewart <pstew@chromium.org>
Commit-Queue: Paul Stewart <pstew@chromium.org>
3 files changed