servo: Merge #10482 - readme: add build status badges (from matthiaskrgr:readme); r=jdm

Preview can be seen here:

https://github.com/matthiaskrgr/servo/tree/readme#the-servo-parallel-browser-engine-project

Source-Repo: https://github.com/servo/servo
Source-Revision: f736d8a261b0291f66100f1f3cd84f80936a2e03

servo/README.md

@@ -1,5 +1,7 @@
 # The Servo Parallel Browser Engine Project
 
+[![Linux Build Status](https://img.shields.io/travis/servo/servo/master.svg?label=Linux%20build)](https://travis-ci.org/servo/servo)  [![Windows Build Status](https://img.shields.io/appveyor/ci/servo/servo/master.svg?label=Windows%20build)](https://ci.appveyor.com/project/servo/servo/branch/master)
+
 Servo is a prototype web browser engine written in the
 [Rust](https://github.com/rust-lang/rust) language. It is currently developed on
 64bit OS X, 64bit Linux, Android, and Gonk (Firefox OS).