Standardize ag_data_access API

Fixes #52 

I standardized the API so that ag_data_access functions return dict (or list of dicts, if more than one row is returned) where the keys to the dict(s) are the column headers from the ```cursor.description```

I also updated test_ag_data_access.py, since it was no longer in sync with the data on webdev-kl4.  This took a long and tedious time, so I **really** think we should put something in place similar to what we have in qiita where the test DB is setup/torn down for each individual test.

Lastly, added some PEP8 fixes and some general code cleanup.