Add decorator expected_errors to V3 servers core

All v3 api should use expected_errors to prevent unexpected exception
raised. This patch add decorator expected_errors for v3 servers core.

Change-Id: Ia1fa09d6cf68a65c85ac5fd2aff9b9202d76e7ca
Closes-Bug: #1343778
Merge "Add decorator expected_errors to V3 servers core"