Change initialize of default source.
Initialize connection handler with argument optional.
Change Manager class to module.
Add require in the Manager module.
Add examples to manager_sepc file.
Remove unused ReservationSystem class.
Fix error on tenant_source_configurations.

When Rails is established the taks and initializer are
executed set the tenant source configurations, in the
first time the source key is deleted and the second time
dosen't exist and rises an error.
Update Railtie to initialize and config Rails tasks.