add travis badge to readme

README.md

@@ -1,7 +1,8 @@
 # VS MEF (Visual Studio's flavor of the Managed Extensibility Framework)
 
 [![NuGet package](https://img.shields.io/nuget/v/Microsoft.VisualStudio.Composition.svg)](https://nuget.org/packages/Microsoft.VisualStudio.Composition)
-[![Build status](https://ci.appveyor.com/api/projects/status/q4uavk7qso20cd9t/branch/master?svg=true)](https://ci.appveyor.com/project/AArnott/vs-mef/branch/master)
+[![Appveyor Build status](https://ci.appveyor.com/api/projects/status/q4uavk7qso20cd9t/branch/master?svg=true)](https://ci.appveyor.com/project/AArnott/vs-mef/branch/master)
+[![Travis-CI Build Status](https://travis-ci.org/Microsoft/vs-mef.svg?branch=master)](https://travis-ci.org/Microsoft/vs-mef)
 [![codecov](https://codecov.io/gh/Microsoft/vs-mef/branch/master/graph/badge.svg)](https://codecov.io/gh/Microsoft/vs-mef)
 [![Join the chat at https://gitter.im/vs-mef/Lobby](https://badges.gitter.im/vs-mef/Lobby.svg)](https://gitter.im/vs-mef/Lobby?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge&utm_content=badge)