mod_http_oauth2: Set content type on successful repsponses (fixes #1501) This will set the content-type on all responses, tho errors are already taken care of in the error handler.

This module blocks configured queries that change server state.

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

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