update CHANGELOG for 1.8.0

Merge pull request drone#85 from shubhag/before_after_attrs

Set before & after attribute for gitlab & bitbucket push event

Merge remote-tracking branch 'origin'

changelog for 1.7.0 [CI SKIP]

update changelog

Merge remote-tracking branch 'origin'

try std and raw std decoding for gitlab contents

Merge pull request drone#20 from ogarcia/commit-by-sha-gogs

Fetch specific commit by sha for gogs, closes drone#7

update status endpoint

added fix for issue drone#15