Add PHP pgsql driver to Dockerfile
Add PHP pgsql driver to Dockerfile

This fixes not being able to use Cachet with Docker and Postgres (with the -e DB_DRIVER=pgsql option)
MatheusRV/Cachet-Sandstorm,robglas/Cachet,n0mer/Cachet,MatheusRV/Cachet-Sandstorm,cachethq/Cachet,NossaJureg/Cachet,MatheusRV/Cachet-Sandstorm,karaktaka/Cachet,MicroWorldwide/Cachet,elektropay/Cachet,ZengineChris/Cachet,wngravette/Cachet,alobintechnologies/Cachet,alobintechnologies/Cachet,bthiago/Cachet,ephillipe/Cachet,sapk/Cachet,pellaeon/Cachet,everpay/Cachet,murendie/Cachet,eduardocruz/Cachet,h3zjp/Cachet,katzien/Cachet,Surventrix/Cachet,leegeng/Cachet,Surventrix/Cachet,whealmedia/Cachet,bthiago/Cachet,Mebus/Cachet,MatheusRV/Cachet-Sandstorm,coupej/Cachet,wakermahmud/Cachet,sapk/Cachet,SamuelMoraesF/Cachet,wngravette/Cachet,cachethq/Cachet,murendie/Cachet,rogerapras/Cachet,karaktaka/Cachet,billmn/Cachet,karaktaka/Cachet,chaseconey/Cachet,g-forks/Cachet,g-forks/Cachet,coupej/Cachet,robglas/Cachet,n0mer/Cachet,ematthews/Cachet,Mebus/Cachet,rogerapras/Cachet,CloudA/Cachet,chaseconey/Cachet,whealmedia/Cachet,nxtreaming/Cachet,elektropay/Cachet,wakermahmud/Cachet,billmn/Cachet,gm-ah/Cachet,pellaeon/Cachet,eduardocruz/Cachet,ematthews/Cachet,ephillipe/Cachet,ematthews/Cachet,Mebus/Cachet,MicroWorldwide/Cachet,anujaprasad/Hihat,MatheusRV/Cachet-Sandstorm,anujaprasad/Hihat,h3zjp/Cachet,chaseconey/Cachet,NossaJureg/Cachet,leegeng/Cachet,billmn/Cachet,NossaJureg/Cachet,sapk/Cachet,CloudA/Cachet,SamuelMoraesF/Cachet,g-forks/Cachet,eduardocruz/Cachet,h3zjp/Cachet,anujaprasad/Hihat,ZengineChris/Cachet,clbn/Cachet,wakermahmud/Cachet,clbn/Cachet,ZengineChris/Cachet,pellaeon/Cachet,gm-ah/Cachet,SamuelMoraesF/Cachet,ephillipe/Cachet,katzien/Cachet,rogerapras/Cachet,nxtreaming/Cachet,displayn/Cachet,elektropay/Cachet,coupej/Cachet,displayn/Cachet,n0mer/Cachet,everpay/Cachet,bthiago/Cachet,murendie/Cachet