mod_http_oauth2: Reflect changes to defaults etc - Resource owner password grant was disabled by default - Tokens now include a hash of client_id making it possible to be reasonable sure that they were issued to a particular client

This module lets you block connections to remote servers at the s2s
level.

``` {.lua}
modules_enabled = {
    -- other modules --
    "s2s_blacklist",

}
s2s_blacklist = {
    "proxy.eu.jabber.org",
}
```