Eliu gh 291 split up schemas file

********* PEOPLE *************
Primary reviewer: @sc932 

Reviewers:

********* DESCRIPTION **************
Branch Name: eliu_gh_291_split_up_schemas_file
Ticket(s)/Issue(s): Closes #291 

split huge schemas.py file into several files under schemas/

********* TESTING DONE *************
make test
visual check of doc changes