Updated phpMyAdmin.conf.erb with full support for Apache 2.4

Support for apache 2.4 was partially implemented and apache 2.4 would not start while including the module.

"AH00526: Syntax error on line 45 of /etc/apache2/conf.d/phpmyadmin.conf:
Invalid command 'Order', perhaps misspelled or defined by a module not included in the server configuration"

With this change, the apache 2.4 starts fine.