Change capitalization of CentOS 7 to Centos 7
Change capitalization of CentOS 7 to Centos 7

I feel like I should elucidate further on my reasoning for this change,
but I'm not going to.

Change-Id: Ie762679c1d491268777da01e9c6a3085e84f3345

Tesora/tesora-project-config,openstack-infra/project-config,Tesora/tesora-project-config,noorul/os-project-config,dongwenjuan/project-config,dongwenjuan/project-config,openstack-infra/project-config,noorul/os-project-config