Test Mac OS X on Travis

[clue]

Squashed by @clue, originally from #124

Resolves / closes #121

[clue]

I've updated this to skip platform-specific (Linux) tests on other platforms (Mac OS X). This is now ready for review

[andig]

I've updated this to skip platform-specific (Linux) tests on other platforms (Mac OS X). This is now ready for review

Alternatively, you could mark the tests with @group and have the OSX or non-Linux build run with --excludeGroup. It's not quite clear why exactly these two tests should be run on Linux only (and not e.g. OSX)?

[clue]

These two tests specifically test system behavior ("how does the server side react to when a client connection is started and aborted immediately without waiting for the connection to be fully established?") and do not really test things specific to this library at all. We know this is how Linux behaves but do not have any reliable source for other platforms, so I think it makes sense to just skip this for now other platforms until we have a better understanding of this.

Our library is known to work perfectly fine on Mac OS X and I think we should emphasize this (failing system specific tests give a wrong impression here). However, our resources to test this on other platforms are limited, I for one for not have a Mac at hand. Given how long this has gone unnoticed, I think it should be sufficient to rely on Travis to spot future regressions here.

@andig I think using a @group makes sense for tests that can/should explicitly be toggled. In this particular case I think it's a sane default to always skip this for Mac OS X 👍

[WyriHaximus]

[WyriHaximus]

@clue @jsor Do we want to test against OS X on all our other packages as well?

[clue]

@WyriHaximus I don't really have a use for this unless anybody brings up any issues, but if you feel it's worth it, I'd say for got it 👍