Action module: Bug fix: define the correct returner function
Action module: Bug fix: define the correct returner function

wikimedia/restbase@18799139 introduced the `ActionService.siteinfo()`
method which relies on `ActionService._doRequest()` to perform the
request. However, the continuation function passed to it had the wrong
signature. This commit fixes the issue.

milimetric/restbase,eevans/restbase,inverno/restbase,gwicke/restbase,wikimedia/mediawiki-services-restbase,Pchelolo/restbase,gwicke/restbase,Pchelolo/restbase,wikimedia/restbase,cscott/restbase,d00rman/restbase,eevans/restbase,milimetric/restbase,wikimedia/restbase,wikimedia/mediawiki-services-restbase,inverno/restbase,cscott/restbase,d00rman/restbase