Added options for external database server

Database config file has allowed only localhost database server. If you
want to use a database on a different host, you need the ability to set
hostname and port
- for MySQL see:
"https://stackoverflow.com/questions/5872264/correct-mysql-configuration-for-ruby-on-rails-database-yml-file"
- for PostgreSQL see:
"https://gist.github.com/jwo/4512764#file-postgres-database-yml"

config/database/database.yml

@@ -14,12 +14,20 @@ default: &default
   # username: zammad
   # password:
 
+  # If the database server is not on localhost, you can set hostname and port:
+  # host:
+  # port:
+
   #### mysql config #####
 
   # adapter: mysql2
   # username: zammad
   # password: <Password>
 
+  # If the database server is not on localhost, you can set hostname and port:
+  # host:
+  # port:
+
 production:
   <<: *default
   database: zammad_production