Change v3 version API to v2.1

This patch changes v3 version API to v2.1 and makes v2 unit tests
share between v2 and v2.1.
v2.1 API does not support XML format. Unit tests related to XML
don't work against v2.1.

Partially implements blueprint v2-on-v3-api

Change-Id: I7abadb0c9082b9e90a98938967f0e27d1a2fa766
Merge "Change v3 version API to v2.1"