Run travis on just node 4. Others don't add much
Run travis on just node 4. Others don't add much

andykog/mobservable,mobxjs/mobx,mweststrate/MOBservable,mobxjs/mobx,andykog/mobservable,mweststrate/MOBservable,mobxjs/mobx,andykog/mobx,andykog/mobx,mweststrate/MOBservable,mobxjs/mobx