Fix 031 migration failed on DB2

031 migration script failed on DB2, because DB2 doesn't support
GROUP BY with clob data type.
Add if condition to judge DB2 connection, if yes, make another sql query
supported by DB2.

Fixes bug #1256816

Change-Id: I7e3a8cd89edd91c167c619365ab863ec53787f8f
VMware storage backend should use oslo.vmware

Currently, the VMware store is using its own copy of the
VMwareApiSession to connect to vCenter server and ESX(i).
This patch gets rid of this copy to use the oslo.vmware library.

Closes-Bug: #1282715

Change-Id: I0aa47eada388c09d9835b00fb2c93f50f22675a4
Merge "Fix 031 migration failed on DB2"
Merge "VMware storage backend should use oslo.vmware"