added mongoid-rspec gem which enables rspec testing for mongoid models
updated readme
added custom validation to Organization model to ensure that an organization has at least one user
removed validation for organization_id from user model so user does not need to be a part of an organization before being created. this will allow the user to create or join an organization after user account creation
added two organization model spec tests
changed required fields validation test and added associations test for the user model
mongoid rspec configuration