When I try to send POST method using this code:
```
const axios = require('axios')
let config = {url: 'http://{{hostname}}', method: 'post'}
let instance = axios.create(config)
instance.request()
```
It send GET method instead of POST.

I think this line https://github.com/mzabriskie/axios/blob/master/lib/core/Axios.js#L37 should be: `config = utils.merge(defaults, this.defaults, config);`
lib/core/Axios.js
this.defaults = instanceConfig;
  this.interceptors = {
    request: new InterceptorManager(),
    response: new InterceptorManager()
  };
}
/**
 * Dispatch a request
 *
 * @param {Object} config The config specific for this request (merged with this.defaults)
 */
Axios.prototype.request = function request(config) {
  
  
  if (typeof config === 'string') {
    config = utils.merge({
      url: arguments[0]
    }, arguments[1]);
  }
  config = utils.merge(defaults, this.defaults, { method: 'get' }, config);
  config.method = config.method.toLowerCase();
  
  var chain = [dispatchRequest, undefined];
  var promise = Promise.resolve(config);
  this.interceptors.request.forEach(function unshiftRequestInterceptors(interceptor) {
    chain.unshift(interceptor.fulfilled, interceptor.rejected);