Software/Slave instance workflow state should now be used to get the expected
status.

status will be not sent. log is not decided yet.

This will allow to directly associate Instance and Hosting Subscription

Creation just creates.

Access and use response object directly.

Thanks to this future compatibility can be easily achieved.

Avoid cluttering vifib_slapos_core.

Providing portal type and tool in same BT5 does not work.

Tool is already present in another BT5.

It is simpler and produces understandable message in case of error.

Also factorise code to avoid repetition and increase readability.