Antenna verification test for router

Added tests to verify each antenna in the router is working.

BUG=chromium:343184
TEST=1. Verify no connection failure when running this test.
     2. To induce a "failure" with this test, manually put a terminator on one antenna in the router.
	Run this test.
	Verify connection failure or connected with weak signal (signal leak from terminator) when the terminated antenna is the only one active

Change-Id: I47e9e01ee6489b013b29d8f36238da9d1e425268
Reviewed-on: https://chromium-review.googlesource.com/187337
Reviewed-by: Christopher Wiley <wiley@chromium.org>
Commit-Queue: Peter Qiu <zqiu@chromium.org>
Tested-by: Peter Qiu <zqiu@chromium.org>
diff --git a/server/site_linux_router.py b/server/site_linux_router.py
index d97e033..4e64a8c 100644
--- a/server/site_linux_router.py
+++ b/server/site_linux_router.py
@@ -111,6 +111,9 @@
         # Place us in the US by default
         self.iw_runner.set_regulatory_domain('US')
 
+        # Reset all antennas to be active
+        self.set_default_antenna_bitmap()
+
 
     def close(self):
         """Close global resources held by this system."""