Added Docs directory

It will be easier to keep a running set of documentation going then to
try to do it later.

Updated sql with user_id for goals. Added all function for database.
Created LineItem and User class
Added GoalType and Account entities

as well as updated SQL table name. I don't want to use classnames with _
in them, it's gross.
Removed ?> from end of php files
Updated Axioms.