Start wendelin.bigfile module

This will be a module to allow users to program custom file-like
backends and latter memory-map content of files from the backend.

For now just start the module structure.

bigfile/__init__.py

+# -*- coding: utf-8 -*-
+# BigFile submodule for Wendelin
+# Copyright (C) 2014-2015  Nexedi SA and Contributors.
+#                          Kirill Smelkov <kirr@nexedi.com>
+#
+# This program is free software: you can Use, Study, Modify and Redistribute
+# it under the terms of the GNU General Public License version 3, or (at your
+# option) any later version, as published by the Free Software Foundation.
+#
+# You can also Link and Combine this program with other software covered by
+# the terms of any of the Open Source Initiative approved licenses and Convey
+# the resulting work. Corresponding source of such a combination shall include
+# the source code for all other software used.
+#
+# This program is distributed WITHOUT ANY WARRANTY; without even the implied
+# warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+#
+# See COPYING file for full licensing terms.