Ability to send params in to a custom operator

Ran across a use case where i wanted to know if a date was at least 5 minutes greater than another date. But if I have other cases like 10 minutes then I need to create operators for each test. If I could send in params with the operator it would allow for some pretty flexible conditions.

```
{
fact: 'date1',
operator: {
operation: 'dateTime-greater',
params: {
unit: 'minute',
quantity: 5
}
},
value: {
fact: 'date2'
}
}
```