Registry recovery does not recover the maintenance object.

Persisted info is fetched from the registry when a master is elected or after failover. Currently, this process involves 3 steps:

• Fetch the "registry".
• Start an operation to add the new master to the fetched registry.
• Check the success of the operation and finish recovering.
  These methods can be found in src/master/registrar.cpp

  RegistrarProcess::recover, ::_recover, ::__recover

Since the maintenance schedule is stored in a separate key, the recover process must also fetch a new "maintenance" object. This object needs to be passed along to the master along with the existing "registry" object.

Possible test(s):

• src/tests/registrar_tests.cpp
  • Change the "Recovery" test to include checks for the new object.