Add the build status

Add the Travis build status to the README (should always be passing due to most changes going through the PR system, but just in case).  Feel free to close-it's not that necessary anyway. :sparkles:

Also, wouldn't the `LICENSE` be better off in the root directory?

And finally, would a `CONTRIBUTING.md` document be appreciated?  Basically all that it does it create a little notice for people to read it before creating a PR (to illustrate repository rules, etc).