Add Travis and code coverage.

Author: hsluoyz

.travis.yml

@@ -0,0 +1,12 @@
+language: go
+
+sudo: false
+
+go:
+  - tip
+
+before_install:
+  - go get github.com/mattn/goveralls
+
+script:
+  - $HOME/gopath/bin/goveralls -service=travis-ci

README.md

@@ -1,4 +1,4 @@
-JSON Adapter [![Godoc](https://godoc.org/github.com/casbin/json-adapter?status.svg)](https://godoc.org/github.com/casbin/json-adapter)
+JSON Adapter [![Build Status](https://travis-ci.org/casbin/json-adapter.svg?branch=master)](https://travis-ci.org/casbin/json-adapter) [![Coverage Status](https://coveralls.io/repos/github/casbin/json-adapter/badge.svg?branch=master)](https://coveralls.io/github/casbin/json-adapter?branch=master) [![Godoc](https://godoc.org/github.com/casbin/json-adapter?status.svg)](https://godoc.org/github.com/casbin/json-adapter)
 ====
 
 JSON Adapter is the [JSON (JavaScript Object Notation)](https://www.json.org/) adapter for [Casbin](https://github.com/casbin/casbin). With this library, Casbin can load policy from JSON string or save policy to it.