Bump version to 1.9.7

Bump version to 1.9.6

fix failing on debug mode (drogonframework#2079)

Bump version to 1.9.5 (drogonframework#2057)

Merge remote-tracking branch 'origin/master' into http2-beta

Fix ChangeLog for beta release

Bump version to 1.9.4

Bump version to 1.9.3

Bump version to 1.9.2

Bump version to 1.9.1