Remove snapshot_id from _volume_snapshot_create()

There is an argument "snapshot_id" in _volume_snapshot_create(), but
the argument is not used in _volume_snapshot_create().
This patch removes it for cleanup.

Change-Id: Ibaad290e149a863c749c74ace3ba702870b8dd1b
Adds a test for raw_cpu_arch in _node_resource

Commit 5fd0500e7e262c602dc7bbbff456326598da41bc
makes it such that the cpu_arch is not
made canonical for scheduling, this adds a unit
test to cover the change.

Change-Id: I89080a0178b1098c2a297b7268fad279ece680c2
Related-Bug: #1366859
Merge "Remove snapshot_id from _volume_snapshot_create()"
Merge "Adds a test for raw_cpu_arch in _node_resource"