Change use of error numbers to errno
Change use of error numbers to errno

The errno constants are more readble in the code.

Change-Id: I6cb4b61f4cf59f50969a7fc27cad35d9c90755f8

seandst/nodepool,citrix-openstack/nodepool,seandst/nodepool,Tesora/tesora-nodepool,Tesora/tesora-nodepool,citrix-openstack/nodepool