[httpd] Serve index.html if requested source is a directory

Defaults to an index.html file instead of redirecting to admin.html. It
will not redirect to index.html, but instead serve the file (if exists)
directly. This allows nicer uris in the webinterface.

We will still redirect to admin.html if no index.html is found for
requests to http://ip:port/

src/httpd.h

@@ -145,11 +145,6 @@ httpd_send_error(struct evhttp_request *req, int error, const char *reason);
 void
 httpd_redirect_to_admin(struct evhttp_request *req);
 
-/*
- * Redirects to [uri]/index.html
- */
-void
-httpd_redirect_to_index(struct evhttp_request *req, const char *uri);
 
 bool
 httpd_admin_check_auth(struct evhttp_request *req);