StorageWizardDialog now runs LocalWebserver in "minimal mode" for
security reasons. In this mode server uses only those handlers which
state to support it.
There are two handlers which support minimal mode: IndexPageHandler
(which handles `code` requests needed by StorageWizardDialog) and
ResourceHandler (which provides inner resources like `style.css` or
`logo.png` from `wwwroot.zip` archive).
Its handlers are now more compact. This commit moves Handler classes in
handlers\ directory.
ResourceHandler ignores "hidden" files in the archive, and these are
used as markup templates in IndexPageHandler and FilesPageHandler.
