add travis ci

Author: jwu

.travis.yml

@@ -0,0 +1,20 @@
+language: node_js
+
+node_js:
+  - "6"
+
+branches:
+  only:
+    - master
+
+cache:
+  - directories:
+    - node_modules
+
+install:
+  - npm install
+
+script: npm test
+
+notifications:
+  email: false

README.md

@@ -1,5 +1,7 @@
 ## vmath
 
+[![Travis CI Status](https://travis-ci.org/gamedev-js/vmath.svg?branch=master)](https://travis-ci.org/gamedev-js/vmath)
+
 Yet another gl-matrix but smaller (without SIMD) and faster (use Hidden class instead of Float32Array).
 
 ## Why?