Run browsers tests with Node.js 8 rather than Node.js 6
Run browsers tests with Node.js 8 rather than Node.js 6

Because standard dev dependencies being installed for not-legacy versions,
has introduced some features or syntax constructs that simply won't
run for Node.js 6 and below.

Therefor running render-and-run-in-browser tests with Node.js 8 instead.

janl/mustache.js,janl/mustache.js,janl/mustache.js,phillipj/mustache.js,janl/mustache.js,phillipj/mustache.js,phillipj/mustache.js,janl/mustache.js,phillipj/mustache.js,phillipj/mustache.js