Jenkins nodes should use go version specified by runtime

[jodh-intel]

The Jenkins config file is installing golang 1.9.2:

• https://github.com/clearcontainers/jenkins/blob/master/config.xml#L110

This is incorrect as we should be installing the golang version specified by go_version= here:

• https://github.com/clearcontainers/runtime/blob/master/versions.txt#L39..L40