Merge pull request #10 from smajda/master

Use templates for email, html and txt.
update version number
email subject as setting
Update README.md
fix markdown syntax.
clarify subject variable name.
Merge branch 'add-subject-as-setting' of https://github.com/grumps/django-nopassword into add-subject-as-setting
Merge pull request #11 from grumps/add-subject-as-setting

email subject as setting
Marked strings for translation and added Spanish translations
Changed from email from `SERVER_EMAIL` to `DEFAULT_FROM_EMAIL`
Merge pull request #12 from tucarga/es-translations

Marked strings for translation and added Spanish translations
Fixed authentication backend

A custom user model without a field called "username" can be used as
`AUTH_USER_MODEL`, the backend now returns `None` for a user model
without a "username" field allowing the next backend (if any) to
handle authentication. Previously it was raising: "FieldError: Cannot
resolve keyword 'username' into field."
Merge pull request #15 from tucarga/auth-backend-custom-user

Fixed authentication backend
Merge pull request #13 from tucarga/default-email

Changed from email from `SERVER_EMAIL` to `DEFAULT_FROM_EMAIL`
update settings in readme, fix #14
bump version number to 0.6
add license
add basic documentation
fix rst syntax in docs
put usage documentation in its own file