- changed the way Range requests are handled:

- changed the way Range requests are handled:
	- do not "advertise" our ability to process ranges at all
	- on hits, handle simple ranges and forward complex ones
	- on misses, fetch the whole document for simple ranges
	  and forward range request for complex ranges
  The change is supposed to decrease the number of cases when clients
  such as Adobe acrobat reader get confused when we send a "200" response
  instead of "206" (because we cannot handle complex ranges, even for hits)
  Note: Support for complex ranges requires storage of partial objects.