Merge branch 'devel-2.5'

* devel-2.5:
  cluster-merge: log an info message at node readd
  Bump version to 2.5.0~rc1
  Fix issue when verifying cluster files
  Revert "utils.log: Write error messages to stderr"
  Fix adding nodes after commit 64c7b383
  LUClusterVerifyGroup: Spread SSH checks over more nodes
  Optimise cli.JobExecutor with many pending jobs

Signed-off-by: Andrea Spadaccini <spadaccio@google.com>
Reviewed-by: René Nussbaumer <rn@google.com>