Added handler to add support for CGI scripts.

Added a new tool `httpd` which is a basic httpd server product (with file server and CGI handler).

tools/httpd/README.md

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+Simple web server
+=================
+
+This server is very simple and limited, it is, for now:
+- a file server
+- a CGI handler (for `*.cgi` executables)
+
+Usage:
+	httpd (--root path)
+
+	--root <path>: document directory for file server (default: www)
+