slapos_web_deploy: Support CentOS 7.4

ansible1.9.noarch is not available on CentOS, so just install standard
ansible. It is >=2.x, but erp5-standalone.yml playbook works with it.

/reviewed-on nexedi/slapos.core!33

master/bt5/slapos_web_deploy/PathTemplateItem/web_page_module/deploy_base_setup.txt

@@ -129,7 +129,11 @@ if is_ubuntu; then
   is_package_installed ansible || install_package ansible=1.*
 elif is_fedora; then
   # is_fedora also handle CentOS distro
+  if [[ "$os_VENDOR" =~ (CentOS) ]] ; then
+    is_package_installed ansible || install_package ansible
+  else
     is_package_installed ansible || install_package ansible1.9.noarch
+  fi
 else
   is_package_installed ansible || install_package ansible
 fi