Provide an abstraction for control interface

Only define/implement APIs for creating proxies for now.

Bug: 24194427
TEST=Compile for both Android and Chrome OS

Change-Id: I55d387abd0104ab808343f244be5acaa8a4c8549
diff --git a/Android.mk b/Android.mk
index dc8c107..f9f0888 100644
--- a/Android.mk
+++ b/Android.mk
@@ -67,6 +67,7 @@
     dbus_bindings/org.chromium.apmanager.Service.dbus-xml \
     config.cc \
     daemon.cc \
+    dbus_control.cc \
     device.cc \
     device_info.cc \
     dhcp_server.cc \