Add librabbitmq requirement for PHP Pecl AMQP.

Fixed dependency error:

[root@dev x86_64]# rpm -ivh php-pecl-amqp-1.4.0-1.el6.5.5.x86_64.rpm 
error: Failed dependencies:
	librabbitmq.so.1()(64bit) is needed by phpu-pecl-amqp-1.4.0-1.el6.5.5.x86_64