Added configuration for HW environment
Cleanup clean ups only prefixied resources
Added ability to select a cloud for cleanup
Migrate servers of all tenants
Do not read yaml files directly
Added evacuation through block migration
Added command to evacuate instances from host
Select resources to migrate by ids/tenant id

Add 2 optional mutually exclusive arguments:
* list of ids of resources to migrate (--id)
* tenant id of resources to migrate (--tenant)

Former is supported for all resource types.
Latter is supported only for resources that can be grouped by
tenant id.

Add function for filtering the list of resources by tenant id.
Add placeholder function to get the list of all resources
of the specified type.
Fix check for empty list
Implement 'all' migration strategy

Function get_all_resource_ids returns a list of IDs of all resources for
the given type of resources.
[doc] Add docstring to functions defining migration strategies