[BUILD] Ignored .idea/copyright

Change-Id: I6fee07c34bccc907367c12aeab81af1cc67eef6e
Reviewed-on: http://saros-build.imp.fu-berlin.de/gerrit/1693
Reviewed-by: Arndt Lasarzik <alasarzik@gmail.com>
Tested-by: Jenkins CI
Reviewed-by: Franz Zieris <zieris@inf.fu-berlin.de>