Add a "Refresh' context menu

[dagwieers]

Since most of the menu listings today are being cached, it would be nice if a listing could be refreshed anew (so not from cache) by selecting 'Refresh' from the context menu. This would then redo the same URI for the listing, but with cache=false appended.

This is equally useful for listings that are not currently cached (e.g. episode listings), as people may expect these listings to have a newer episode too (i.e. waiting for an episode to come online as expected from TV guide).

[dagwieers]

The original implementation was too invasive.
Now we simply invalidate the specific cache and refresh the container.