Validations and errors

-created validations for when a user signs up, or signs in to TravelFlow

-a new user is requires to have a name and a unique email, in the correct email format

-when creating a new account, it will generate errors if the email format is incorrect, or if the name is missing

-when signing in, if the password or email are incorrect, it will generate a flash error

-if user signs in, or logs in successfully, a flash message will confirm this