Implementing user demographics collection.

models: Adding the LeadUserInfo class. Each instance is uniquely linked
to a single user. Saved to the app_leaduserinfo database.
registration_form: Adding fields for demographics collection and
validation.
views: Adding creation of user info along with user.
User registration form changes

Changing the user registration form to subclass ModelForm and splitting
the LeadUserInfo input off into a separate form - each form handles
input validation and object creation according to its model. Allows for
greater flexibility in adding content and creates ‘less moving parts’
for simplicity.
Changing views to work with two forms and allow each form to handle
object creation and saving to db.