Tests should be possible to run on something else than OSX

[ferd]

The current tests use "open -a " to start up a browser and get things going. This command works on OSX only. We should try to find [at least] a Linux equivalent in order to make it possible for more people to develop on socket.io-erlang, including myself on my personal laptop.

An idea to help with this that was mentioned on IRC would be to use Meck to build mocks representing the default behaviour of a client+server discussion. We test these mock objects on OSX to make sure they work, and then make them canonical for our suite so we can run them on Linux, but also make them public so we can allow other developers building their own products on top of socket.io-erlang use them to test their products with more ease. This could then become a full-blown feature and likely a competitive advantage over any other socket.io implementation out there.