authpolicy: Implement daemon and D-Bus interface with Samba stub

Provides complete D-Bus interface with two new methods to refresh
user and device policy. Separates main/daemon from D-Bus interface
implementation and adds Samba interface stub to be implemented in a
subsequent CL. The D-Bus methods will be called by Chrome to
authenticate, join a device to a AD domain and fetch policy.

Code requires the CL below to compile.

BUG=chromium:653509
TEST=Emerges. Daemon runs, but just stub code so far.

CQ-DEPEND=CL:403068

Change-Id: Ic5eb4621f1c21fccc26e7e3f656b6751fdceba96
Reviewed-on: https://chromium-review.googlesource.com/403872
Commit-Ready: Lutz Justen <ljusten@chromium.org>
Tested-by: Lutz Justen <ljusten@chromium.org>
Tested-by: Roman Sorokin <rsorokin@chromium.org>
Reviewed-by: Lutz Justen <ljusten@chromium.org>
Reviewed-by: Roman Sorokin <rsorokin@chromium.org>
15 files changed