Enable/disable building of QA views (refs #7545)

Adds a new configuration option, `CouchDb.SyncQAViews`, read by
the sync_couch_views.py script. The `Couch().sync_views()` method
now also accepts a `sync_qa_views` argument. If `CouchDb.SyncQAViews`
is not set, the QA views will be synced by default.