Add leadSource data to User

Closes #4

lib/user.rb

@@ -13,7 +13,8 @@ class User
       email:      email,
       firstName:  first_name,
       lastName:   last_name,
-      signUpDate: Date.today
+      signUpDate: Date.today,
+      leadSource: 'GitLab.com'
     }
   end
 end