CA-125187: Add copy to VDI current_operations

Signed-off-by: John Else <john.else@citrix.com>
CA-125187: VBD allowed_operations fix

VBD allowed_operations checks should ignore running VDI.copy operations.
This wasn't needed before as VDIs weren't marked with the copy
operation.

Signed-off-by: John Else <john.else@citrix.com>