add exten/dialplan myself

Thanks to VitalPBX:

Create  extensions__80-1-mydialplan.conf in /etc/asterisk/ombutel/

	[cos-all-custom](+)
	exten => 1234,1,Answer()
	;;Play mesage in English:
	exten => 1234,n,agi(googletts.agi,"This is a simple google text to speech test in english.",en)