The deployment branch can have the registration to be confirmable.

The link sent to the email needs to be clicked and verified in order
to complete the registration process
Added one more line in the devise.rb file.

As mentioned on the readme of the devise github repository
Moved line from devise.rb -> application.rb

THe line given in the README is to be added in the application.rb file
inside the config/ folder and not in the devise.rb initializer.