Reformat gwas.py and combine_figures.py

[ofrei]

Fixes #127

Changes proposed in this pull request:

• formatted python scripts to better comply with the style guide

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[ofrei]

@espenhgn #126 worked very well, I squashed and merged in order to rebase my commits changing gwas.py (this PR).
If these changes are OK please merge. Best to use "rebase" - I'd like to keep those four commits separately, this way it'll be easier to spot any issue if this reformatting has introduced a regression. But test_gwas_py.py passes just fine )

[espenhgn]

Looks good to me!

[espenhgn]

@ofrei, please delete branch https://github.com/comorment/containers/tree/fix-127 if it's no longer needed.