mod_http_upload: Duplicate mime types handling from mod_http_files (fixes #1374) When using net.http.files this isn't automatically provided via mod_http_files so we need to do it ourselves.

This module blocks configured queries that change server state.

E.g. to make vCard storage read-only:

``` lua
readonly_stores = {
	vcard = { "vcard-temp", "vCard" };
}
```