Update readme with Travis badge (#16)

And remove redundant header info

Author: kevmoo

README.md

@@ -1,7 +1,7 @@
-# Dart gRPC
-
-This repository contains a [Dart](https://www.dartlang.org/) implementation of
+A [Dart](https://www.dartlang.org/) implementation of
 [gRPC](https://grpc.io/).
 
+[![Build Status](https://travis-ci.org/dart-lang/grpc-dart.svg?branch=master)](https://travis-ci.org/dart-lang/grpc-dart)
+
 ***Note***: This implementation is in a very early & experimental state. We do
 not recommend using it for anything but experiments.