tests: Ignore more error messages for hidden rules test.

tests: Ignore more error messages for hidden rules test.

This test intentionally configures an unreachable controller.  It ignored
some error messages in the log, specifically
    br0: cannot find route for controller (240.0.0.1): ...
but a bug report says that other forms of messages can also appear, e.g.
    br0<->tcp:240.0.0.1:6653: connection dropped (No route to host)
This commit therefore expands the logged error messages that will be
ignored to any message that includes the IP address 240.0.0.1.

Reported-by: "Kurek, Tytus" <Tytus.Kurek@pega.com>
Reported-at: http://openvswitch.org/pipermail/discuss/2015-September/018910.html
Signed-off-by: Ben Pfaff <blp@nicira.com>
Acked-by: Justin Pettit <jpettit@nicira.com>