Review and changes from Jocelyn Fiat

I replaced the compute_hash_ha1 and so on because apart from the wikipedia page this is not obvious to know the meaning.
So it is better to have expressive name here. In addition before it was also used from the DEMO_... class, so it was bad to have such function with misterious name for the user.
Now that the Authentication Info header value is also provided by the HTTP_AUTHORIZATION class, this is now just an implementation function, and it could have been hash_a1 for instance .. but let's keep the new name.

In addition `compute_hash_a1' is a bad name for a function ... it could have been  `hash_a1' , but compute_ or get_ ... would make me think that this is a procedure that compute a value hash_a1 .. that could be an attribute, or that could be accessed by a function `hash_a1'

In Eiffel, we do care a lot about naming, since it improves readability of the code, better to maintain code, and we tend to have a common style (or rule) for any code, so that any Eiffel coder can work on any code without any effort to understand the style.