Travis test fixes

2 very simple changes.

The first redirects stderr to stdout for the comparison tool so that c-i can see that the test is doing something.
The second keeps the port# from exceeding 65535 on a busy machine.
For a minute I was confused whether it is allowed to use port 65535, but apart from some remarks that 49152+ is 'ephermal port range', which is advisory, I could not find anything conclusive, and binding on port 65535 was no problem when I tried. But it may nevertheless make sense to use a safety margin here.