slapos.cookbook: Add _failsafe publish type recipes

In some contexts it's required to not stop buildout processing on publishing
errors, thus such recipe is required in those cases.

By providing -error-status-file it's possible to check status of the publish,
the file will be created on error and removed on successful call or during
uninstall. It's responsibility of the caller to handle such errors, for example
by using proper promises.