Merge pull request #40 from aerth/master

Use travis-ci

.travis.yml

+language: go
+sudo: false
+addons:
+    apt:
+        packages:
+            - xorg-dev
+            - libx11-dev
+            - libxrandr-dev
+            - libxinerama-dev
+            - libxcursor-dev
+            - libxi-dev
+go:
+- 1.8
+- 1.7.4
+- tip 
+install:
+- go get -t ./...
+script:
+- go test -i -race ./...
+- go test -v -race ./...
+

README.md

-# Pixel [![GoDoc](https://godoc.org/github.com/faiface/pixel?status.svg)](https://godoc.org/github.com/faiface/pixel) [![Go Report Card](https://goreportcard.com/badge/github.com/faiface/pixel)](https://goreportcard.com/report/github.com/faiface/pixel) [![Join the chat at https://gitter.im/pixellib/Lobby](https://badges.gitter.im/pixellib/Lobby.svg)](https://gitter.im/pixellib/Lobby?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge&utm_content=badge)
+# Pixel [![Build Status](https://travis-ci.org/faiface/pixel.svg?branch=master)](https://travis-ci.org/faiface/pixel) [![GoDoc](https://godoc.org/github.com/faiface/pixel?status.svg)](https://godoc.org/github.com/faiface/pixel) [![Go Report Card](https://goreportcard.com/badge/github.com/faiface/pixel)](https://goreportcard.com/report/github.com/faiface/pixel) [![Join the chat at https://gitter.im/pixellib/Lobby](https://badges.gitter.im/pixellib/Lobby.svg)](https://gitter.im/pixellib/Lobby?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge&utm_content=badge)
+
 
 A hand-crafted 2D game library in Go. Take a look into the [features](#features) to see what it can
 do.