Added iPython merging, piping and SGE support.

iPython is now used as the backend for handling loading
using schedulers via the ipython-cluster-helper repo.

Loading now pipes the output from grabix directly to
load_chunk to avoid hitting the disk.

SGE support for loading added via the sge_queue option.
Merged upstream.
Removed superflous print statement.
Merge pull request #82 from roryk/master

Added iPython interaction, speeded up merging/loading steps.