Merge commit 'quintela/migration-next-v5' into staging

Merge commit 'quintela/migration-next-v5' into staging

* commit '6c779f22a93cc6e4565b940ef616e3efc5b50ba5':
  Change ram_save_block to return -1 if there are no more changes
  ram: save_live_setup() we don't need to synchronize the dirty bitmap.
  ram: iterate phase
  ram: save_live_complete() only do one loop
  ram: save_live_setup() don't need to sent pages
  savevm: split save_live into stage2 and stage3
  savevm: split save_live_setup from save_live_state
  savevm: introduce is_active method
  savevm: Refactor cancel operation in its own operation
  savevm: remove SaveLiveStateHandler
  savevm: remove SaveSetParamsHandler
  savevm: Live migration handlers register the struct directly
  savevm: Use a struct to pass all handlers