[Student View] Preview module before publishing it

[AdamGripton]

The ability to preview what a module of individually published resources would look like to a student BEFORE publishing the module itself. At present you need to actually publish the module before "student view" will work properly, otherwise you get an error message saying it's not published yet.

This is particularly important when courses have been ported from another platform and we need to make sure links to images display properly (i.e. have themselves been properly published).