update travis node version
update travis node version

mattbell87/brackets-git,zaggino/brackets-git,zaggino/brackets-git,mattbell87/brackets-git,MarcelGerber/brackets-git,MarcelGerber/brackets-git,zaggino/brackets-git,mattbell87/brackets-git,zaggino/brackets-git,MarcelGerber/brackets-git,MarcelGerber/brackets-git