change DB_URL to DATABASE_URL so heroku works

Author: m4v15

database/db_connection.js

@@ -2,9 +2,9 @@ const { Pool } = require('pg');
 const url = require('url');
 require('env2')('./config.env');
 
-if(!process.env.DB_URL) throw new Error('Environment variabel DB_URL must be set');
+if(!process.env.DATABASE_URL) throw new Error('Environment variabel DATABASE_URL must be set');
 
-const params = url.parse(process.env.DB_URL);
+const params = url.parse(process.env.DATABASE_URL);
 const [username, password] = params.auth.split(':');
 
 const options = {