jenkins/tools: Explicitly include phantomjs

We already install npm/phantomjs via npm/grunt-lib-phantomjs, but
let's include it explicitly as well.

Using version "~1.9.0-1" since that is what our versin of grunt
uses, this way we avoid using slightly different versions within
Jenkins, and it allows NPM to share the module depedency instead
of duplicating it.

Change-Id: I14ec3d7b3e348501d626a96d4bef681c9e40b429