Work on docstrings for drug response application

[jonesse3]

The files included are:

• config.py
• drug_utils.py
• omics_utils.py
• drp_utils.py

@adpartin I'll work on this, and have it tested and completed by next week (11/14).

[jonesse3]

Pull request per file was submitted @adpartin. Tested all files together in this branch with tCNNS preprocess script and it worked.