Remove copyright from empty files in nova

Sync I9043bf2f646de880afccbb64e47b257aba3ca599 to nova

According to policy change in HACKING:
http://docs.openstack.org/developer/hacking/#openstack-licensing
empty files should no longer contain copyright notices.

Change-Id: Id194e118dfdd140fda4fd00d2398d7818d590257
Partial-Bug: #1262424
Merge "Remove copyright from empty files in nova"