Updated a few comments

Removed useless NULL_HTTP_CLIENT.
Extracted mime code from NET_HTTP_CLIENT_REQUEST.response into specific routine.

library/network/http_client/src/default/libcurl_or_net/default_http_client.e

@@ -1,6 +1,9 @@
 note
 	description: "[
-			Default HTTP_CLIENT based on LIBCURL_HTTP_CLIENT.
+			Default HTTP_CLIENT based on LIBCURL_HTTP_CLIENT or NET_HTTP_CLIENT.
+			
+			The preference goes to libcurl implementation for now,
+			since the net implementation has currently less functionalities.
 		]"
 	author: "$Author$"
 	date: "$Date$"

library/network/http_client/src/default/null/default_http_client.e

@@ -10,6 +10,24 @@ class
 	DEFAULT_HTTP_CLIENT
 
 inherit
-	NULL_HTTP_CLIENT
+	HTTP_CLIENT
 
+feature -- Access
+
+	new_session (a_base_url: READABLE_STRING_8): HTTP_CLIENT_SESSION
+			-- Create a new session using `a_base_url'.
+		do
+			create {NULL_HTTP_CLIENT_SESSION} Result.make (a_base_url)
+		end
+
+note
+	copyright: "2011-2015, Jocelyn Fiat, Javier Velilla, Eiffel Software and others"
+	license: "Eiffel Forum License v2 (see http://www.eiffel.com/licensing/forum.txt)"
+	source: "[
+			Eiffel Software
+			5949 Hollister Ave., Goleta, CA 93117 USA
+			Telephone 805-685-1006, Fax 805-685-6869
+			Website http://www.eiffel.com
+			Customer support http://support.eiffel.com
+		]"
 end