Watch upstream breaking change

What does this MR do and why?

relate #185 (closed)

watch upstream breaking change mr and create jh watching issue

以下是用的到环境变量

update_after = ENV['UPSTREAM_BREAKING_CHANGE_AFTER'] || (Date.today - 1).to_s # expect 2019-03-15
upstream_group = ENV['UPSTREAM_BREAKING_CHANGE_GROUP_ID'] || 9970 # by default upstream gitlab-org group
upstream_labels = ENV['UPSTREAM_BREAKING_CHANGE_LABELS'] || 'breaking change,high-risk-change'
ENV['JH_TARGET_PROJECT'] || Triage::GITLAB_CN_GITLAB
ENV['JH_BREAKING_CHANGE_LABEL'] || 'breaking change'