Add libesphttpd to extras and supporting example (#458)

* libesphttpd: added extras and example

* Added "heatshrink" as a submodule

* Updated libesphttpd

* Updated libesphttpd

* Trying to fix the commit id

* Updated libesphttpd

* Added zlib1g-dev package

* Use native gcc to build mkespfsimage and mkupgimg

* Added NS and GW for DHCP server configuration

examples/esphttpd/io.h

@@ -0,0 +1,7 @@
+#ifndef IO_H
+#define IO_H
+
+void ICACHE_FLASH_ATTR ioLed(int ena);
+void ioInit(void);
+
+#endif