Change to gunicorn and update variable names

env.example

@@ -1,7 +1,6 @@
-IP=0.0.0.0 # Lisen on all interfaces
-PORT_NUMBER=8080 # Internal port number
+LISTEN_ADDRESS=0.0.0.0 # Lisen on all interfaces
+LISTEN_PORT=8080 # Internal port number
 MPV_SOCKET=/tmp/mpvsocket # Path to mpv socket
-LOGLEVEL=info
 
 # MySQL connection info
 MYSQL_HOST=localhost
@@ -10,3 +9,4 @@ MYSQL_PASSWORD=SecretPassword
 MYSQL_DATABASE=mpv
 MYSQL_PORT=3306
 
+LOGLEVEL=info