Fix wrong logic prestart (#5)

* fix wrong logic in prestart script

configs/app/prestart.sh

@@ -1,6 +1,6 @@
 #!/bin/bash
 
-if [ "${DB_VENDOR}" = "mariadb" ] || [ "${DB_VENDOR}" = "mysql" ]; then
+if { [ "${DB_VENDOR}" = "mariadb" ] || [ "${DB_VENDOR}" = "mysql" ]; } then
     echo "Using $DB_VENDOR..."
     [ -z "$DB_HOST" ] && echo "DB_HOST should be defined" && return 1
     [ -z "$DB_USER" ] && echo "DB_USER should be defined" && return 1
@@ -22,7 +22,7 @@ if [ "${PI_SKIP_BOOTSTRAP}" = false ]; then
     fi
     pi-manage createdb
     pi-manage db stamp head -d /usr/local/lib/privacyidea/migrations/
-    if [ -z ${PI_ADMIN_USER}] && [ -z ${PI_ADMIN_PASSWORD} ]; then
+    if { [ -z ${PI_ADMIN_USER} ] && [ -z ${PI_ADMIN_PASSWORD} ]; } then
         echo "Create deafult admin user. Not recommented in production. Please set PI_ADMIN_USER and PI_ADMIN_PASSWORD in production enviroment."
         pi-manage admin add admin -p privacyidea
     else