Merge pull request node-fetch#291 from bitinn/2.x-npm-5-release

2.0.0-alpha.5 release

Merge pull request node-fetch#290 from bitinn/1.x-npm-5-release

1.7.1 release

1.7.0

get ready for alpha 4 release

v2.0.0-alpha.1

See [changelog](https://github.com/bitinn/node-fetch/blob/master/CHANGELOG.md#v200-alpha1) for details

1.6.3

1.6.2

1.6.1

1.6.0