Add cmake3 to image

Dockerfile

@@ -3,7 +3,9 @@ FROM centos:6
 RUN 	sed -i '/^mirrorlist/s/^/#/;/^#baseurl/{s/#//;s/mirror.centos.org\/centos\/$releasever/vault.centos.org\/6.10/}' /etc/yum.repos.d/*B* ; \
 	yum -y update && yum clean all ; \
 	yum -y groupinstall -y "Development Tools" ; \
-	yum -y install cmake
+	yum -y install cmake ; \
+	yum -y install epel-release ; \
+	yum -y install cmake3
 
 CMD ["/bin/bash"]