Checking if unconfirmed_email has changed before to set update_needs_confirmation flash message.
Show invalid confirmation token message

fixes #2143

Attribute confirmation token is not present in the simple_form template,
therefore not being displayed by #error_notification.
This fix explicitily call #full_error on :confirmation_token.
Show invalid unlock token message

Attribute unlock token is not present in the simple_form template,
therefore not being displayed by #error_notification.
This fix explicitily call #full_error on :unlock_token.
Use correct current_password in RegistrationTest of invalid confirmation

In DatabaseAuthenticatable#update_with_password, password is now deleted if
the current_password is invalid. dm-validations will not check the
confirmation in that case, so this test was failing in dm-devise.
Merge pull request #2144 from jm81/master

Use correct current_password in RegistrationTest of invalid confirmation
Support alternate sign in error message when email record does not exist

By default, the nonexistent error is still identical to the :invalid
message, and must be customized by the developer to implement.
Fix typo on nonexistent error
Fix default email_regexp config to not allow spaces

Default email_regexp config accepted emails with spaces. e.g.: "test user@test server.com" http://rubular.com/r/jXGS8pmumd
Changed regexp to not allow spaces in email. e.g.:  http://rubular.com/r/tTD9PytGEp
Used other regxp
Merge pull request #2143 from luisico/display-invalid-confirmation-token-error

Invalid confirmation token message not shown with simple_form
Update README.md
add test for Devise.email_regexp
Change failure key for missing database resource to :invalid_email
Merge pull request #2147 from gabetax/signin_nonexistent_error

Support alternate sign in error message when email record does not exist
Merge pull request #2148 from kukula/master

Fix default email_regexp config to not allow spaces
minor documentation grammar update
Merge pull request #2164 from asanghi/master

Minor grammar updates
reverting part of #2164 which was a mistake
Merge pull request #2165 from asanghi/master

Reverting part of #2164 which was a mistake [ci skip]
Move test models into their own file so they can be used elsewhere