Allow scc check-milestone to correct wrongly assigned milestones

Previously, scc check-milestone was skipping the milestone edition if any
milestone was assigned to a PR. With this commit, the title of the milestone
(assumed to be unique) is additionally checked and a new milestone is
reassigned if applicable.
merge master -Dorg -Ssuccess-only: PR 186 (Comment on possible conflicts)
merge master -Dorg -Ssuccess-only: PR 191 (Allow scc check-milestone to correct wrongly assigned milestones)
merge master -Dorg -Ssuccess-only

Repository: openmicroscopy/snoopycrimecop
Already up-to-date.

Merged PRs:
  # PR 186 manics 'Comment on possible conflicts'
  # PR 191 sbesson 'Allow scc check-milestone to correct wrongly assigned milestones'

Generated by SCC-merge#450 (http://ci.openmicroscopy.org/job/SCC-merge/450/)