Adding a file array to tell NPM what we want to publish. (#3)

Adding a file array to package.json tell NPM what we want to publish. Resolves issue #4

Implement callbacks for oncomplete and onloopcomplete (#2)

* Implement callbacks for oncomplete and onloopcomplete

- onLoopComplete func prop added
- onComplete func prop added
- Misc tidy up and bug fixes

* Changed props to support duration rather then Speed as that can be universally controlled on web and native.
- BREAK: REMOVED SUPPORT FOR SPEED AS IT CANT BE CONTROLLED CROSS PLATFORM

* Add props info to README