tutorials: Renamed .org -> .orig

See http://www.openfoam.org/mantisbt/view.php?id=2076
  - .org is the file extension for emacs org-mode as well
  - .orig is more to the point (.org isn't always recognized as "original")
  - .original is too long, although more consistent with the convention
    of source code file naming

Update script contributed by Bruno Santos

tutorials/multiphase/interFoam/ras/weirOverflow/Allrun

@@ -3,11 +3,11 @@
 # Source tutorial run functions
 . $WM_PROJECT_DIR/bin/tools/RunFunctions
 
-cp -r 0.org 0 > /dev/null 2>&1
+cp -r 0.orig 0 > /dev/null 2>&1
 
 runApplication blockMesh
 
-cp 0/alpha.water.org 0/alpha.water
+cp 0/alpha.water.orig 0/alpha.water
 
 runApplication setFields