Add node 9.8.0, remove node 9.7.0
Add node 9.8.0, remove node 9.7.0

source url: https://nodejs.org/dist/v9.8.0/node-v9.8.0.tar.gz
source sha256: e84a1baf8248411d2c875c2f4e519878af3fb62fdfe04f9607cc085e6a0e59d6

[#155804707]

cloudfoundry/nodejs-buildpack,cloudfoundry/nodejs-buildpack,cloudfoundry/nodejs-buildpack,cloudfoundry/nodejs-buildpack