mod_http_muc_log: Drop support for pre-0.11 MUC API The oldest supported Prosody branch is 0.11, therefore we can drop code for the MUC API of Prosody 0.10 and before. The module:shared("rooms") method was never even in a release...

This module blocks configured queries that change server state.

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

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