Enable absolute imports for modules using Queue.

When running on Linux with code on a case-insensitive file system,
imports of the `Queue` module fail because python resolves the
wrong file (It is trying to use a relative import of `queue.py` in
the kafka directory). This change forces absolute imports via PEP328.
Merge pull request #66 from jcrobak/fix-import-collision

Enable absolute imports for modules using Queue.