The SQL query here, as written, was omitting 'log' type messages from
the results.

Signed-off-by: Malf Furious <m@lfurio.us>

Update all usage of saveFile() to use added saveIfFile() function,
forwarding on the convenience to model code.  Model code can pass in
file field names, rather than $_FILES arrays directly.

We can check for the existence of an object's background image by
calling getBgImg(), since it returns NULL when there is no such image.
But getHeadImg() behaves differently, returning a path to
'static/img/null.jpg' (via df.php) when there is no image, making it
more difficult to tell.  This function addresses this concern.

Added a $limit argument to specify a maximum number of results to
return.