Update Travis CI

Go to the read me and read the sentence
On Thu, Aug 21, 2014 at 11:21 AM Nikita Pekin <notifications@github.com>
wrote:

> In README.md:
>
> >
> >  This is a parser for the wavefront .obj file format. There are informative
> >  error messages with line number reporting. The full file format is not
> > -supported, although patches for adding support for unimplemented parts of the
> > +supported, although patches for adding support for unimplemented parts of the format are very welcome.
> >  format are very welcome.
>
> Do you mean the full sentence, or the line break?
>
> —
> Reply to this email directly or view it on GitHub
> <https://github.com/PistonDevelopers/wavefront-obj/pull/6/files#r16556961>
> .
>