a batch of additions

 * `string-stream-appender` and `with-logged-output-to-place` to
   concatenate many log messages into an in memory string
 * add-signal-handler for adding default log signal-handlers
 * abort restarts around appending and logging, so that handlers can
   decide to just skip appending a message

re ADWolf:#1243
Some improvements, better logstash control and abort while generating
message

 * with-logstashing-only, without-logstashing,
   with-concatenated-logstash-logs
 * abort while generating messages works now