[Integrated] RFR: Make it possible to cancel a Check

[duke]

Changeset: fc526853
Author:    Erik Helin <ehelin at openjdk.org>
Date:      2019-10-04 07:29:31 +0000
URL:       https://git.openjdk.java.net/skara/commit/fc526853

Make it possible to cancel a Check

Co-authored-by: Robin Westberg <robin.westberg at oracle.com>
Reviewed-by: rwestberg

! bots/pr/src/test/java/org/openjdk/skara/bots/pr/CheckTests.java
! host/src/main/java/org/openjdk/skara/host/CheckBuilder.java
! host/src/main/java/org/openjdk/skara/host/CheckStatus.java
! host/src/main/java/org/openjdk/skara/host/github/GitHubPullRequest.java
! host/src/main/java/org/openjdk/skara/host/gitlab/GitLabMergeRequest.java