[5.5] Clear real-time facades when running artisan cache:clear

[calebporzio]

@taylorotwell - the app I am actually working on is 5.4, what is the best way to get this fix into 5.4 as well?

[taylorotwell]

This fix will only work if you are actually using the file cache driver. We may want to put the logic in the cache flush command itself. Also, tests are failing.

[calebporzio]

@taylorotwell - good call, moved the logic into the clear command itself.