Don't modify injected_files inside PXE driver

Make a local copy of injected_files so that we don't modify the
original.

Change-Id: I508cfc0baec15a091a1717eb2aebb9dd39278e5b
use nova-conductor for live-migration

The function check_can_live_migrate_source in compute/manager.py
attempts to make a direct DB query. This small change makes the
query through the conductor service

Change-Id: I9edc0aec89b4ce030f20020204e7c872f2f4fbd8
fixes: bug 1124594
Merge "use nova-conductor for live-migration"
Merge "Don't modify injected_files inside PXE driver"