Calendar's organizer set to its owner

The synchronization mechanism was overwritten and includes a
ESClient.getUsers call.  Values returned from these calls are set as
organizerId (username) and organizerCN (realname attribute)
properties.
Calendar's organizer set to its owner

Calendar properties organizerId and organizerCN have sensible default
now if server doesn't provide enough data.  The defaults are derived
from indentity in case a calendar is owned by Thunderbird identity use
it current context.  Otherwise, both properties are set to null.