MNT: Added back deprecated extract_noise script

fsl/scripts/extract_noise.py

+#!/usr/bin/env python
+#
+# extract_noise.py - Deprecated - replaced by fsl_ents.py
+#
+# Author: Paul McCarthy <pauldmccarthy@gmail.com>
+#
+"""This module is deprecated - it has been replaced by :mod:`.fsl_ents`. """
+
+
+import sys
+
+
+if __name__ == '__main__':
+    print('extract_noise is deprecated and will be removed in fslpy 2.0. '
+          'Use fsl_ents instead.')
+    from fsl.scripts.fsl_ents import main
+    sys.exit(main())