shill: cellular: Add Cellular.ICCID property.

This CL exposes the SIM identifier in CellularCapabilityUniversal as a
DBus property 'Cellular.ICCID' on the device object.

BUG=chromium-os:33120
TEST=Tested the following:
1. Build and run unit tests.
2. Verify that shill includes Cellular.ICCID property on a
   cellular device when available.

Change-Id: I18a4363edb5b6fde180a3232be71c2e527c6c05a
Reviewed-on: https://gerrit.chromium.org/gerrit/28859
Reviewed-by: Gary Morain <gmorain@chromium.org>
Commit-Ready: Ben Chan <benchan@chromium.org>
Tested-by: Ben Chan <benchan@chromium.org>
diff --git a/device.cc b/device.cc
index db0616f..a654811 100644
--- a/device.cc
+++ b/device.cc
@@ -113,6 +113,7 @@
   // flimflam::kEsnProperty: Registered in Cellular
   // flimflam::kHomeProviderProperty: Registered in Cellular
   // flimflam::kImeiProperty: Registered in Cellular
+  // flimflam::kIccidProperty: Registered in Cellular
   // flimflam::kImsiProperty: Registered in Cellular
   // flimflam::kManufacturerProperty: Registered in Cellular
   // flimflam::kMdnProperty: Registered in Cellular