Loading db nulls as empty strings and final tweaks

...assuring the model runs produced from R objects loaded from db match
the runs from the prototypical R objects, which were  used to populate
those tables in the first place.
Merge pull request #4 from johnmannpaul/2013-14-Data-Model

Merge pull request #3 from johnmannpaul/master
Merge pull request #5 from johnmannpaul/master

Syncing with master