thttpd THTTPD webserver

This is a port of Jef Poskanzer's THTTPD HTPPD server. See http://acme.com/software/thttpd/ for general THTTPD information. See apps/include/netutils/thttpd.h for interface information. Applications using this thttpd will need to provide the following definitions in the defconfig file to select the appropriate netutils libraries:

CONFIG_NETUTILS_NETLIB=y
CONFIG_NETUTILS_THTTPD=y