Update travis badge for master branch only
Update travis badge for master branch only

I'm abandoning git-flow for a much simpler branching model:

    https://gist.github.com/jbenet/ee6c9ac48068889b0912

Since the master branch must always be deployable, it makes sense to show the
travis badge for the master branch only.

aparente/Dotfiles,aparente/Dotfiles,aparente/Dotfiles,nilehmann/dotfiles-1,aparente/Dotfiles,Bklyn/dotfiles