Avoids double queries on view/view.php and view/artefact.php, where a
View object is constructed from an id inside can_view_view, and again
on the page.

Change-Id: I0f034f04765f73d64758b6ff7ec11c5cbdcdb6f7
Signed-off-by: Richard Mansfield <richard.mansfield@catalyst.net.nz>