"get_pseudo_sdrf.py" and "gen_spreadsheets.py"

[dongbohu]

The management command adage/analyze/management/commands/import_experiments_samples.py calls the following two modules:

• get_pseudo_sdrf.py
• gen_spreadsheets.py

They were originally written in a Python 2 repo: https://bitbucket.org/greenelab/get_pseudomonas/

We need to factor out these two modules so that they are compatible to both Python 2 and Python 3 (and maybe port the whole get_pseudomonas repo to Python 3 too).