filterOptions should accept an object

## Expected Behavior
`filterOptions` should also accept an object for dropdowns.

## Current Behavior
Right now we can only provide an array for `filterOptions`. This might be okay for client-side filtering but we could also use an object for server-side filtering cases.

```
filterOptions: { enum_1: "Enum 1", enum_2: "Enum 2" } // Render "Enum 1"
...
onTableChange: (action, tableState) // At this point I prefer to get "enum_1" value
```