shill: Connection: UnPin routes on destruction

Tag pinned routes with the interface index associated with the request,
so they can be removed when the connection is destroyed.  Also move
PinHostRoute() out of the VPN code and into the Connection.

BUG=chromium-os:29911
TEST=New unit tests

Change-Id: I46019255276469929642db4a6395e64f53e3b7d5
Reviewed-on: https://gerrit.chromium.org/gerrit/20982
Commit-Ready: Paul Stewart <pstew@chromium.org>
Reviewed-by: Paul Stewart <pstew@chromium.org>
Tested-by: Paul Stewart <pstew@chromium.org>
diff --git a/openvpn_driver.h b/openvpn_driver.h
index e73fabd..b2b7ba5 100644
--- a/openvpn_driver.h
+++ b/openvpn_driver.h
@@ -14,6 +14,7 @@
 #include <gtest/gtest_prod.h>  // for FRIEND_TEST
 
 #include "shill/glib.h"
+#include "shill/ipconfig.h"
 #include "shill/refptr_types.h"
 #include "shill/rpc_task.h"
 #include "shill/service.h"