Update for deprecation of selectFields() methods

Authored by Anomie on Oct 12 2017, 7:44 PM.

Description

Update for deprecation of selectFields() methods

Various selectFields() methods were deprecated in MediaWiki core change
Idcfd1556. This change adapts the extension to use the replacement
getQueryInfo() methods when available.

Depends-On: Idcfd15568489d9f03a7ba4460e96610d33bc4089
Change-Id: I42237e8e29497bbc56606f6ad01de3d525bf8b2a