Actually, this name in last version was ServiceManagerFactory, but lmr thought it is too long. Then I rename it to Factory in this version.

 I think it is okey here. we can use is as below:

a) using it in namespace of service.
```
from virttest.staging import service

service.Factory.create_service()
```
b) use it alone.
```
from virttest.staging.service import Factory as ServiceManagerService

ServiceManagerService.create_service()
```
Then user will not be confused by a name of Factory.