OS-563, uppercase network_type during extrattr creation

I think we need to additionally check that resulting network type is in allowed range: [ VXLAN, GRE, STT, VLAN ]
Because if it is not network creation will fail not NIOS.
So we should show clear message for user that 'network can not be created because network type %type is not in allowed network types range  [ VXLAN, GRE, STT, VLAN ]'