Merge pull request #101 from CentOS/master

add CentOS7 image, update CentOS 6 image both 20140707

library/centos

@@ -1,4 +1,5 @@
 # maintainer: The CentOS Project <[email protected]> (@CentOS)
 
-latest: git://github.com/CentOS/sig-cloud-instance-images@7976905d428bfdd9a704fe560abff4363c4706fc docker
-centos6: git://github.com/CentOS/sig-cloud-instance-images@7976905d428bfdd9a704fe560abff4363c4706fc docker
+latest: git://github.com/CentOS/sig-cloud-instance-images@dbcffd71d9e7ddc3168df7653f9d83323ba43a05 docker
+centos7: git://github.com/CentOS/sig-cloud-instance-images@dbcffd71d9e7ddc3168df7653f9d83323ba43a05 docker
+centos6: git://github.com/CentOS/sig-cloud-instance-images@c5a1d99681cf08990e9873c0a8880d0f61a43a48 docker