added sign in page, sign up page, validations to User model for uniqueness, email, password length, and uncommented session delete method in controller sessions
Merge branch 'master' of https://github.com/cassiemoy/survey_gorilla_group_project into derek
Merge pull request #11 from cassiemoy/derek

added sign in page, sign up page, validations to User model for uniqueness, email, password length, and uncommented session delete method in controller sessions