Update CHANGELOG.md

Update CHANGELOG.md for release 2.17.0

Update changelog for 2.16.6

Merge pull request github#174 from github/aibaars-patch-1

Update CHANGELOG.md for release 2.16.5

Merge pull request github#173 from github/angelapwen/update-changelog…

…-2.16.4

Update CHANGELOG.md for release 2.16.4

Merge pull request github#171 from github/smowton/admin/update-change…

…log-2.16.3

Update CHANGELOG.md for release 2.16.3

Update chanelog for 2.16.2

Update changelog for 2.16.1

Update CHANGELOG.md for 2.16.0

Update changelog for 2.15.5