Added --show-variant-samples option to gemini_query

This which adds a column to the output listing all
samples containing a variant (HET or HOM_REF).
Added total, het and hom_alt columns to --show-variant-samples.
Added --sumarize option to stats.

--summarize plus a query will summarize the amount of het
and hom_alt variants each samples has returned by the query.
Added slightly less awful naming.
Added documentation for --show-samples and --summarize.
Formatting fix.
Formatting fix.
Fixes for reported installation issues: new version of ipython-cluster-helper with only IPython 0.13.2 requirement; better error message for missing configuration data; only require configured data when doing loading to allow other functionality to work without data files. Thanks to Amit Indap
Merge pull request #147 from roryk/master

Added optional column of which samples have a variant to queries.
Merge pull request #152 from chapmanb/master

Fixes for reported installation issues
Update requirements.txt