authentificate user upon signin/signup, also session out upon signout
authentificate user upon signin/signup, also session out upon signout

nyc-rock-doves-2015/asian_power_survey_gorilla,nyc-rock-doves-2015/asian_power_survey_gorilla,bkmorimoto/survey-gorilla,nyc-rock-doves-2015/asian_power_survey_gorilla,bkmorimoto/survey-gorilla,bkmorimoto/survey-gorilla