User Registration & Authentication

As a new user I can sign up with my email and password, so that so that I can create a personal account and access my checklists.

Acceptance criteria 1: When I provide a valid email, first name, last name, and password, then my account should be created.
Acceptance criteria 2: When I log in, I should be redirected to the dashboard.
Acceptance criteria 3: When I try to sign up with the same email again, then I should see an error message indicating that the email is already in use
Acceptance criteria 4: Progress retained between sessions

craigallendev / django-checklist