fixed build issues of debian/ubuntu

First, I've added a control.template for making debian package. 

In addition, I've changed architecture choosing rule. The logic of my patch is that if there is no 'arch' specified in package's index.yaml or system-wide default.yaml it will set self->info->data->{arch} to the architecture of current box using 'uname -m'.   

Moreover, though x86_64 debian reports its arch 'x86_64', debian is actually not comfortable with this string. So, I've added some code to replace 'x86_64' with 'amd64' which is debian's flavor. 

I've tested this patch on my ubuntu and CentOS 6. it works and it seems not to break other things.

Thanks very much.