remove dup connection names to avoid collision in async calls in tests

remove duplicate inproc file names to avoid collision in async calls inside of tests.

Here is an example of this code failing prior to this patch.
   https://travis-ci.org/f34rdotcom/zeromq.node/jobs/36637964

Again this is nearly impossible to reproduce but I will continue to rebuild on Travis through the night to try and test as well as look for other issues. In any case the docs are clear on Mocha that one should not expect tests to complete in sequence especially when a test makes calls to IO.

Now we just need to watch for someone submitting tests that have this pattern of multiple tests and make sure no socket reuse is happening.