Object/named array in query string
I wanted to validate a object in query string (`?deactivated[from]=2019-05-23T08:18:45.283Z&deactivated[to]=2019-06-12T08:18:45.283Z`)
So I went ahead and tried:
```
query: {
  deactivated: {
    from: Joi.date(),
    to: Joi.date(),
  },
}
```
But the request just prints out (`"deactivated[from]" is not allowed`).

I have discovered that `?deactivated={"from": "2019-01-01T08:18:45.283Z"}` works, but I would like the use the first approach, as that's how objects are converted to query string by default.
Is there any way I can get this behaviour?


From further testings, if I define the query like so:
```
query: {
  "deactivated[from]": Joi.date(),
  "deactivated[to]": Joi.date(),
}
```
It seems to work, but that's not a solution, the variable names are unusable.