Merge branch 'stable-2.5' into devel-2.5

Merge branch 'stable-2.5' into devel-2.5

* stable-2.5:
  listrunner: Don't pass arguments if there are none
  ssh: Quote strings in error message
  utils.log: Write error messages to stderr
  Add signal handling doc to hbal man page
  Fix handling of cluster verify hooks
  Redistribute the RAPI certificate
  QA: Add tests for instance start/stop via RAPI
  RAPI: Fix wrong check on instance shutdown
  baserlib: Accept empty body in FillOpcode

Signed-off-by: Andrea Spadaccini <spadaccio@google.com>
Reviewed-by: Guido Trotter <ultrotter@google.com>