tests: Change to parse dynamically allocated ports on windows.

tests: Change to parse dynamically allocated ports on windows.

In Windows, we use kernel assigned TCP port for ssl/tcp and
unixctl. In tests, we parse the log files of ovsdb-server.log,
test-sflow.log and test-netflow.log to get this port. In all
the above cases, tcp port is allocated first and then the unixctl port.
So a 'head -1' on the result should be safe.

Signed-off-by: Gurucharan Shetty <gshetty@nicira.com>
Acked-by: Ben Pfaff <blp@nicira.com>