Add Node 4 to Travis
Add Node 4 to Travis

Kikobeats/async,jnordberg/async,caolan/async,moander/async,llwanghong/async,Segeon-Kim/async,andalm/async,steverobb/async,caolan/async,SaiNadh001/async,renruixi/async,ezubarev/async,arigo-software/async,llwanghong/async,jamesjnadeau/async,steverobb/async,suguru03/async,jamesjnadeau/async,mcanthony/async,andalm/async,jaruba/async,moander/async,Segeon-Kim/async,rlugojr/async,rlugojr/async,mcanthony/async,ecasilla/async,zhhb/async,zhhb/async,jnordberg/async,ezubarev/async,Segeon-Kim/async,renruixi/async,hargasinski/async,ecasilla/async,jaruba/async,SaiNadh001/async,hargasinski/async,Kikobeats/async,arigo-software/async,suguru03/async