conda recipe and binstar build yml file

This aids building bcolz with conda and hosting conda builds on binstar-build.

Note that the Blaze channel is [hosting bcolz builds](binstar.org/blaze/bcolz/builds) for all platforms and common Python versions.  These are accessible via the following:

    conda install -c blaze bcolz

This doesn't require a compiler and tends to point to something closer to git master than the main conda channel.

Also, just for acknowledgements, I stole a fair amount of this work from others, notably @cpcloud .
you could add ``--always`` and ``--dirty`` to the ``git describe`` command, to make it work in even more circumstances.