Added null http client for upcoming changes.

Refactored NET request implementation.
  - fixed potential issue with header conflict.
  - simplified, and extract parts of the code into routine.
  - Implemented read of chunked Transfer-Encoding
  - Fixed potential issue with socket handling.
First steps to be able to exclude net or libcurl implementation when using http_client lib.
Removed from NET implementation the hack related to PUT and upload data (it was used to workaround an issue with libcurl).

library/network/http_client/src/http_client.e

@@ -16,7 +16,6 @@ feature -- Status
 		deferred
 		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)"