Change PF handling; include site in getTargets

* Simplify and move verifyPFData
  * We don't need to check if URL is well-formed; if not it'd fail on
    getDBName
* Always include the 'site' key in MassMessage::getTargets for
  consistent behaviour
* Index databases by host:port if port is specified
* Use getBaseUrl($wgCanonicalServer) instead of $wgServerName in some
  places

Change-Id: Ic0ce01bd6954db02e10d9674454297d80582f5ea