To generate a certificate for multiple domains, you will need to modify your openssl.cnf. See here: http://stackoverflow.com/questions/21488845/how-can-i-generate-a-self-signed-certificate-with-subjectaltname-using-openssl
just change out app_name for your purposes
openssl genrsa 2048 > app_name-wildcard.key
openssl req -new -x509 -nodes -sha1 -days 3650 -key app_name-wildcard.key > app_name-wildcard.cert