Strict Verify Mode

It is now possible to enforce that all commits in a PR build successfully before PR can be merged
Strict mode merge check no longer fails fast

This ensures that all commits missing verify builds are reported
Merge pull request #73 in ATLASP/stashbot-helper from feature/strictmode to master

* commit '19c806e0c8da220d326583d4e3abeb53259fae72':
  Strict mode merge check no longer fails fast
  Strict Verify Mode
Make sure PR merge is --no-ff for consistency

Some verify builds might want to compare the history being merged - for consistency, we should ensure there is always a merge commit.
Merge pull request #74 in ATLASP/stashbot-helper from feature/noff to master

* commit 'fb3ea0e37783c1f533f6bdaaac56e9624e851469':
  Make sure PR merge is --no-ff for consistency