v3.2.0-rc0

Merge branch 'stable-3.1'

* stable-3.1:
  Clarify the limitations of gerrit+ssh in replication.config
  PushOne: Don't log refs to push at ERROR level
  PushOne: Remove redundant 'throws' declarations
  Destination: Further improve the debug logs when not pushing
  Improve logging of why a project or ref is not replicated
  ReplicationQueue: Add handling of null ReplicationTasksStorage.ReplicateRefUpdate
  Destination: Extract repeated string to a constant
  Fix flaky ReplicationConfig tests
  FanoutReplicationConfig: Make methods static where possible
  Factor out and simplify the check if Path is a *.config file
  Consistently use Files.list in FanoutReplicationConfig
  Add multiple replication configuration file support
  Use ReplicationConfig interface instead of ReplicationFileBasedConfig
  Fix failing AutoReloadConfigDecorator tests
  Move replication config parsing out of DestinationsCollection
  Extract destinations logic into a new class
  ReplicationQueue: Migrate to Flogger

Adapt existing replication logging code in master to Flogger,
to allow the merged code to build successfully on master.

Change-Id: Ice4e54ab5c1a1a53894432c3687137e4b3603c41