Changed observer to listen to the post dispatch event because the admin session isn't initialised when the predispatch event is triggered. Fixed checkTfaSubmitted method to avoid  infinite loop and allow logout. http://alanstorm.com/magento_sessions_early.
Change store name to username@hostname
Added option to disable TFA entirely or just for the frontend
Updated help messages
Merge pull request #1 from aligent/develop

Merging changes from develop branch