Turn ido-everywhere on again

I switched this off when I installed ido-ubiquitous, but it seems like
ido-ubiquitous isn't completing dired commands (like copying files).
I've set `ido-ubiquitous-allow-on-functional-collection', but that
didn't seem to fix it. I should ask upstream and see if I'm missing
anything obvious, but for now I'm going to turn ido-everywhere on again
I expect some clashes between it and ido-ubiquitous, but without looking
at how both are implemented, it's hard to know.