Implement {Available|Connected|Enabled}Technolgies and DefaultTechnology

This is Part 1 of a series of changes required for the Manager to generate
the right set of DBus events allowing shill to properly tell Chrome about
connectivity.

Some other side-effects in the change (needed to implement the above):
- Emit these manager properties over DBus everytime we re-sort the Service
  vector.
- Add a technology data member to Device, this allows easy enumeration of
  technologies.
- Add interface for getting a handle to the selected service on a device.
- Map connected state to online instead of ready state. This is needed for
  so that Chrome doesn't wait for the portal detection code to switch the
  state from ready->online.
- Default set the ethernet service as connectable.

BUG=chromium-os:14887
TEST=1) manual test to verify shill properly configures the ethernet
     device and Chrome correctly detects that.
     2) new unit tests

Change-Id: Ib10f2f0836f8d4aacaad1491f58ed9b3b5d37e7d
Reviewed-on: https://gerrit.chromium.org/gerrit/12019
Tested-by: Gaurav Shah <gauravsh@chromium.org>
Reviewed-by: mukesh agrawal <quiche@chromium.org>
diff --git a/ethernet.cc b/ethernet.cc
index f8e2b55..8fe8caf 100644
--- a/ethernet.cc
+++ b/ethernet.cc
@@ -37,7 +37,8 @@
              manager,
              link_name,
              address,
-             interface_index),
+             interface_index,
+             Technology::kEthernet),
       service_registered_(false),
       link_up_(false) {
   VLOG(2) << "Ethernet device " << link_name << " initialized.";