HTTP 302 and 304 Support

Add support for http redirection (302) and http not modified (304) to
reduce the load the server.
server.redirect(“url”, “location”, exclude-ip) will respond with 302 to
redirect the browser to a different url, this is useful for backward
compatibility and to redirect call to CDN when not no AP mode.
server.serveStatic has a new optional parameter to get the
Last-Modified date for all files serve for this location, when the
browser request have the same If-Modified-Since header value, the
server respond with 304 code instead of serving the file.

README.md

@@ -416,6 +416,38 @@ server.addHandler( new FileFallbackHandler(_fs, "/jquery/jq1.11.1.js" , "/jquery
 server.addHandler( new FileFallbackHandler(_fs, "/jquery/jqm1.4.5.js" , "/jquery/jqm1.4.5.js" ,   "http://code.jquery.com/mobile/1.4.5/jquery.mobile-1.4.5.min.js",  "max-age=86400"));
 ```
 
+### Serving static files from SPIFFS
+Serve a specific file or attach a folder in SPIFFS to a root url.
+An optional Cache-Control header can be added to responses.
+An optional Last-Modified header can be added, if the request contains If-Modified-Since header with the same value the server will respond with 304 code instead of serving the file.
+```cpp
+
+// Serve static file example
+server.serveStatic("/url/file.htm", SPIFFS, "/dir/file.htm");
+// Serve static folder example
+server.serveStatic("/root-url", SPIFFS, "/root-dir");
+// Specify cache control
+server.serveStatic("/root-url", SPIFFS, "/root-dir", "max-age=86400");
+// Specify last modified (should be updated each time files are updated)
+server.serveStatic("/root-url", SPIFFS, "/root-dir", NULL, "Wed, 08 Jun 2016 22:00:00 GMT");
+
+```
+
+### HTTP Redirect (302)
+Return HTTP 302 response to redirect the client to a different location.
+An optional IPAddress can specify redirection exclusions, for example, exclude redirection to requests to the AP address.
+```cpp
+// Redirect all requests
+server.redirect("/root/file.ext", "/other-location/other-file.ext");
+// Redirect requests not for the AP address
+server.redirect("/root/file.ext", "/other-location/other-file.ext", WiFi.softAPIP());
+
+// Redirect to jquery CDN except when call is done to AP address
+server.redirect("/jquery/jq1.12.3.js", "http://code.jquery.com/jquery-1.12.3.min.js", WiFi.softAPIP());
+// Serve the jquery from SPIFFS
+server.serveStatic("/jquery", SPIFFS, "/jquery");
+
+```
 
 ## Bad Responses
 Some responses are implemented, but you should not use them, because they do not conform to HTTP.