Add test support, fix existing problems and add Travis CI support

As per comments from https://github.com/paulmillr/Array.prototype.find/issues/1 from @mathiasbynens and @sindresorhus:

- Added test support
- Added the [applicable ES6 Shim tests](https://github.com/paulmillr/es6-shim/blob/master/test/array.js)
- Fixed implementation to pass all tests(!) ('*should work with an array-like object with negative length*')
- Added Travis Support
- Bumped all versions to 0.2.0
- Added acknowledgements where appropriate