added uniqueness logic for user when donating - also added prelim address creation code, but need to sort out name collision with Paypal sdk gem class
added update_amount_raised callback
put manual create of users to bottom to prevent problems in sampling users for donations
commented out address creation for now until paypal naming conflict is fixed
added default values to migrations
changed dollar columns from integer to decimal
Merge pull request #17 from alancohen/controllers

uniqueness logic for donating users, update_amount_raised callback, dollars stored as decimals, fixed seed files, more validations in migration