added user model

front-api/models/user.rb

@@ -0,0 +1,9 @@
+class User < ActiveRecord::Base
+  has_secure_password
+  validates_presence_of :first_name, :last_name, :password, :email, :password_confirmation
+
+  validates :email, :uniqueness => {:case_sensitive => false, :message => "Email already exists!"},
+    format: { with: /\A([^@\s]+)@((?:[-a-z0-9]+\.)+[a-z]{2,})\z/i, message: "invalid email" }
+
+  validates :password, confirmation: true, length: { in:6..20, too_short: 'password needs to be at least 6 characters long' }
+end