attach & detach volumes apis for compute

Change-Id: I1a7abcfc83f581601c730d93440dca7d447a53a0
Complete net-show/net-list/subnet-list/subnet-show

Change-Id: I0047c14eee758c1a283cdc53757544c45994faf3

Defect - replace self allocation_pool calculation with ipaddress - ip_network call

Change-Id: I0c131a65e884ac48646f8c2602d33e53d1316d83
Merge pull request #117 from ajiang38740/net-subnet-list-show-improvement

Complete net-show/net-list/subnet-list/subnet-show
Merge pull request #118 from ajiang38740/volume_attach_detach

attach & detach volumes apis for compute