Should channels be case insensitive? or maybe just always lower case?

I need to test it, but I think this would broadcast to two different channels:

```crystal
Channel.broadcast_to("room:1", "hi")
Channel.broadcast_to("ROOM:1", "hi")
```

I feel like it should always be the same, and if it's not, then we should make that change. But if you're expecting `"Room"`, then all of a sudden send `"room"` and it doesn't work, that would be a breaking change