chore(release): 2.0.0-rc.1 [skip ci]

## [2.0.0-rc.1](v1.5.0...v2.0.0-rc.1) (2020-12-09)

### ⚠ BREAKING CHANGES

* **cancellation:** The Deferral class no longer has cancellation.

### Features

* **cancellation:** implement cancellation in the FunPromise itself instead of in Deferral ([4da84e7](4da84e7))
* **return:** add in the 'return' method a la Bluebird ([a1c84a4](a1c84a4))

### Bug Fixes

* **funpromise:** remove unused variable ([0b7e034](0b7e034))