Changelog update for 1.6.0

Bump version: 1.5.0 → 1.5.1

Merge pull request scrapy-plugins#71 from scrapy-plugins/changelog

1.5.0 Changelog

Merge pull request scrapy-plugins#61 from hcoura/1.4.0

Bump version: 1.3.0 → 1.4.0

Bump version: 1.2.4 → 1.3.0

Bump version: 1.2.3 → 1.2.4

Bump version: 1.2.2 → 1.2.3

Bump version: 1.2.1 → 1.2.2

Bump version: 1.2.0 → 1.2.1

Bump version: 1.1.0 → 1.2.0