Allow testing Baidu by setting BAIDU_KEY environment variable
Allow testing Baidu by setting BAIDU_KEY environment variable

This change updates index.test.js to look for the BAIDU_KEY environment
variable and, if it is set, test the Baidu endpoint.

$ BAIDU_KEY='abc' npm test

I've not managed to sign up for a Baidu key to test this.

zhso/reverse-geocoding