[lxc] provide centos 7 example
[lxc] provide centos 7 example

pecigonzalo/packer,p1-nico/packer,taliesins/packer,KohlsTechnology/packer,dave2/packer,grubernaut/packer,markpeek/packer,mitchellh/packer,tas50/packer,tas50/packer,pieter-lazzaro/packer,ChrisLundquist/packer,smaato/packer,taliesins/packer,hashicorp/packer,p1-nico/packer,bryson/packer,ChrisLundquist/packer,c22/packer,grubernaut/packer,atlassian/packer,rnaveiras/packer,paulmey/packer,pieter-lazzaro/packer,pvandervelde/packer,pecigonzalo/packer,youhong316/packer,jen20/packer,pieter-lazzaro/packer,ChrisLundquist/packer,sean-/packer,ricardclau/packer,bryson/packer,pvandervelde/packer,rnaveiras/packer,smaato/packer,timsutton/packer,mkuzmin/packer,KohlsTechnology/packer,rnaveiras/packer,sean-/packer,c22/packer,jen20/packer,taliesins/packer,arizvisa/packer,mitchellh/packer,jen20/packer,tb3088/packer,paulmey/packer,pieter-lazzaro/packer,taliesins/packer,tas50/packer,pieter-lazzaro/packer,timsutton/packer,tas50/packer,pecigonzalo/packer,dave2/packer,routelastresort/packer,mkuzmin/packer,atlassian/packer,tas50/packer,routelastresort/packer,pieter-lazzaro/packer,tb3088/packer,grubernaut/packer,paulmey/packer,hashicorp/packer,ricardclau/packer,youhong316/packer,sean-/packer,routelastresort/packer,jen20/packer,c22/packer,sean-/packer,sean-/packer,tb3088/packer,ricardclau/packer,atlassian/packer,ChrisLundquist/packer,mitchellh/packer,c22/packer,arizvisa/packer,arizvisa/packer,c22/packer,paulmey/packer,pvandervelde/packer,grubernaut/packer,ChrisLundquist/packer,smaato/packer,ChrisLundquist/packer,mitchellh/packer,mkuzmin/packer,p1-nico/packer,bryson/packer,markpeek/packer,timsutton/packer,jen20/packer,smaato/packer,arizvisa/packer,timsutton/packer,pvandervelde/packer,KohlsTechnology/packer,smaato/packer,sean-/packer,rnaveiras/packer,pecigonzalo/packer,rnaveiras/packer,mkuzmin/packer,p1-nico/packer,markpeek/packer,markpeek/packer,arizvisa/packer,youhong316/packer,dave2/packer,markpeek/packer,bryson/packer,tb3088/packer,smaato/packer,timsutton/packer,bryson/packer,KohlsTechnology/packer,tas50/packer,grubernaut/packer,taliesins/packer,rnaveiras/packer,hashicorp/packer,grubernaut/packer,bryson/packer,mkuzmin/packer,atlassian/packer,tb3088/packer,atlassian/packer,p1-nico/packer,youhong316/packer,ricardclau/packer,p1-nico/packer,pvandervelde/packer,KohlsTechnology/packer,youhong316/packer,ricardclau/packer,dave2/packer,KohlsTechnology/packer,arizvisa/packer,routelastresort/packer,pvandervelde/packer,ricardclau/packer,jen20/packer,routelastresort/packer,atlassian/packer,paulmey/packer,markpeek/packer,dave2/packer,hashicorp/packer,timsutton/packer,tb3088/packer,youhong316/packer,taliesins/packer,paulmey/packer,dave2/packer,mitchellh/packer,mkuzmin/packer,c22/packer