Simplified bootstrap candidate DNS resolver.
Phasing out several DNS entries.
Perform tasks after Dispersy has started.
Add new DNS entries for our bootstrap servers.
Report call-stack when an exception occurs.

Even when the process isn't killed by it, we should still see where the
exception originated from, this is essential for debugging the problem.
Catch socket.error exception.

By catching the specific socket.error exception we allow the Callback to
properly interrupt the task by raising a GeneratorExit exception.  Also,
it is good coding practice to specify the exception you want to catch.
Even simpler.
Shorter thread name.

A shorter name will allow us to see the thread number in top/ps.
A timeout is considered -not- successful.
Avoid additional resolve.

Previous code could (depending on threading conditions) cause
bootstrap.resolve to be called twice.  It wouldn't actually resolve
anything (since it was most likely already done) but moving the test
after the yield will avoid the warning and additional thread creation.
Remove undefined DNS entries.

The DNS entries pointing to the machine outside the TUDelft have not
been configured (yet?).
Log exception where they are caught.
Merge pull request #172 from boudewijn-tribler/simplify-bootstrap

Simplified bootstrap candidate DNS resolver.