Bug 1537426: Ignore site blogs/blogposts im menus options

Now that 'mahara' can have blog/blogpost artefacts we want to ignore
them from site menus options for logged in links

Change-Id: I8d1be32678ae97d93187181eb4aedcb331e543eb
Signed-off-by: Robert Lyon <robertl@catalyst.net.nz>
(cherry picked from commit 130890b2)