Add ability to specify rsync options

Added new flag '--rsync-options' to allow to use internal rsync options,
like '--link-dest' during mirror syncing on local machine to keep disk
space. Example:

parameters:
  debmirror:
    client:
      mirrors:
        mirror_name:
          ...
          <current parameters>
          ...
          rsync_options: [ '--link-dest=<path-to-dir>' ]

Change-Id: Id39275e66d08c056790fccc993597e17d208e812
Related-bug: PROD-22539
1 file changed