added next= to registration button
refs #280 made participation request text more direct and clearer. Now a user just clicks a 'participate' link and is requested to log in/register if needed, instead of telling them to log in/register explicitly
fixes #280. My best attempt. Very frustrating struggle with userena. In the end getting custom information into the standard userena activation email would mean completely taking over many of the functionality of userena. Not worrying about implementing all of that is exactly why we use userena.
Merge branch 'dev'