Upload form for nodemcu-httpserver

Now you can update your files in /http directory of your tiny webserver
over Wi-Fi!

Drag&drop or browse one or multiple files.
List uploaded files.
Delete files.
Automatically rename files to http/(filename)
Automatically compile .lua files.
Shows total/used memory.
You must compile upload.lua file!

Have some bugs but works pretty well even for uploading lot of files.

http/index.html

@@ -29,6 +29,7 @@
       <li><a href="node_info.lua">NodeMCU info</a>: Shows some basic NodeMCU(Lua)</li>
       <li><a href="file_list.lua">List all server files</a>: Displays a list of all the server files. (Lua)</li>
       <li><a href="foo.html">Foo</a>: A file that doesn't exist. Should error (404 error)</li>
+	  <li><a href="upload.html">Upload</a>: update, remove, list files on the server.</li>
    </ul>
 </body>
 </html>