Added high-impact burden summary and c-alpha test.
Added scipy as a dependency.
Merge branch 'master' of github.com:arq5x/gemini
Merged.
New subtool: burden tests, added.

Run with no special arguments calculates
a table of the number of high impact variants
per gene per sample.

Run with --nonsynonymous it calculates the
same table, but looking at all non-synonymous
variants.

Run with --calpha, it runs the c-alpha test,
using case/control status as specified in
the sample table

Run with --calpha and optional --cases and
--controls lists of samples  runs the c-alpha test
with those samples set as cases and controls.

Unit tests added, along with necessary data files.
Added scipy and pandas as dependencies.
Added burden test documentation.
Fixed formatting.
Added PID to logging messages.
Merge branch 'master' of github.com:roryk/gemini
Merge pull request #167 from roryk/master

burden testing