Rename VCSBaseClient::settingsChanged() to handleSettingsChanged().
This avoids confusion with a signal (note : Bazaar and Mercurial
plugins are impacted)

Change-Id: I8afd8d60be300088081338a4ed682c2760ba42eb
Merge-request: 358
Reviewed-by: Tobias Hunger <tobias.hunger@nokia.com>
Reviewed-on: http://codereview.qt.nokia.com/3336