Remove node 0.6 from Travis CI.
Remove node 0.6 from Travis CI.

Trult/passport,shubham13jain/passport,ernestopino/passport,Faiz7412/passport,imjerrybao/passport,bartuspan/passport,dentrinh/passport,pandeysoni/passport,arover/passport,wakashige/passport,kidaa/passport,mcanthony/passport,qitianchan/passport,kolomiichenko/passport,jaredhanson/passport,modulexcite/passport,DaAwesomeP/passport,jameswomack/passport-restify