File Upload Fixes

Dunno why this was buggered again. ":back" doesn't seem to function as it used to.
Also, when uploading a file from page "foo", it's important to return to "foo" after
a successful upload, rather than redirecting to the HomePage.

Finally, a favicon tweak.

app/controllers/file_controller.rb

@@ -18,7 +18,7 @@ class FileController < ApplicationController
       new_file = @web.wiki_files.create(params['file'])
       if new_file.valid?
         flash[:info] = "File '#{@file_name}' successfully uploaded"
-        redirect_to_page(@page_name)
+        redirect_to(params['referring_page'])
       else
         # pass the file with errors back into the form
         @file = new_file