Fix the failing dns test on Windows

Gets the name of the first interface on the system. Windows network
interfaces don't have the same name across Window systems. YOu can even
go as far as naming them whatever you want. The test was failing because
the interface name was hard-coded as 'Ethernet'.

tests/integration/modules/test_win_dns_client.py

@@ -22,8 +22,12 @@ class WinDNSTest(ModuleCase):
         '''
         Test add and removing a dns server
         '''
+        # Get a list of interfaces on the system
+        interfaces = self.run_function('network.interfaces_names')
+        skipIf(interfaces.count == 0, 'This test requires a network interface')
+
+        interface = interfaces[0]
         dns = '8.8.8.8'
-        interface = 'Ethernet'
         # add dns server
         self.assertTrue(self.run_function('win_dns_client.add_dns', [dns, interface], index=42))