Removed storage configuration from nova.conf when doing unconfigure

Issue: unconfigure of livem didnt remove the storage_scope from
nova.conf. This caused local VMs spawn to fail.
Fix: Removed the storage_scope from nova.conf during unconfigure
Closes-Bug: #1366669

Change-Id: Idf2fdc5f677f38ff3b4a25bc3b81ba8eb6ea2eb3