This is the git default and will help to prevent false positive matches.

Closes #12706

# Conflicts:
#	spec/lib/gitlab/markdown/autolink_filter_spec.rb
#	spec/lib/gitlab/markdown/commit_range_reference_filter_spec.rb
#	spec/lib/gitlab/markdown/commit_reference_filter_spec.rb
#	spec/lib/gitlab/markdown/cross_project_reference_spec.rb
#	spec/lib/gitlab/markdown/emoji_filter_spec.rb
#	spec/lib/gitlab/markdown/external_issue_reference_filter_spec.rb
#	spec/lib/gitlab/markdown/external_link_filter_spec.rb
#	spec/lib/gitlab/markdown/issue_reference_filter_spec.rb
#	spec/lib/gitlab/markdown/label_reference_filter_spec.rb
#	spec/lib/gitlab/markdown/merge_request_reference_filter_spec.rb
#	spec/lib/gitlab/markdown/redactor_filter_spec.rb
#	spec/lib/gitlab/markdown/reference_gatherer_filter_spec.rb
#	spec/lib/gitlab/markdown/relative_link_filter_spec.rb
#	spec/lib/gitlab/markdown/sanitization_filter_spec.rb
#	spec/lib/gitlab/markdown/snippet_reference_filter_spec.rb
#	spec/lib/gitlab/markdown/syntax_highlight_filter_spec.rb
#	spec/lib/gitlab/markdown/table_of_contents_filter_spec.rb
#	spec/lib/gitlab/markdown/task_list_filter_spec.rb
#	spec/lib/gitlab/markdown/upload_link_filter_spec.rb
#	spec/lib/gitlab/markdown/user_reference_filter_spec.rb

Add added, modified and removed properties to commit object in webhook

https://gitlab.com/gitlab-org/gitlab-ee/issues/20

See merge request !1988