Apply this transform using jscodeshift to remove most chai-as-promised assertions.

> Note: this codemod does not cover all of the `assert.eventually` cases, but they should be easy to add.

There's really no alternative to defining the function `assert.isRejected`. The following should approximate the functionallity from chai-as-promised.

```js
var chai = require('chai');

  Assertion.addMethod('isRejected', function expectedRejection(promise, expected) {
    return promise
      .then(function(actual) {
        this.assert(
          false,
          'expected #{this} to be rejected but it was fulfilled with #{act}',
          null,
          expected,
          actual
        );
        return actual;
      }.bind(this),
      function(reason) {
        if (expected) {
          if (expected instanceof RegExp || typeof expected === 'string') {
            this.match(reason, expected);
          }

          if (expected instanceof Error) {
            this.instanceOf(reason, expected);
          }


        }
      }.bind(this));
  });
```