Cleanup: remove redundant, invalid info from headers

BF-admins agree to remove header information that isn't useful,
to reduce noise.

- BEGIN/END license blocks

  Developers should add non license comments as separate comment blocks.
  No need for separator text.

- Contributors

  This is often invalid, outdated or misleading
  especially when splitting files.

  It's more useful to git-blame to find out who has developed the code.

See P901 for script to perform these edits.

source/blender/collada/BCAnimationSampler.cpp

@@ -1,5 +1,4 @@
 /*
-* ***** BEGIN GPL LICENSE BLOCK *****
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
@@ -20,7 +19,6 @@
 *
 * Contributor(s): Blender Foundation
 *
-* ***** END GPL LICENSE BLOCK *****
 */
 
 #include <vector>