Add the ability to convert values in CSV filter

This PR adds the ability to use the converters option on the CSV parser - this allows end users to quickly convert values based on it's type - IE: Convert INTs etc to INTs automaticly. 


you could use something more ruby here 

```ruby
['a','b','c'].map!(&:to_sym) unless @converters.nil?
```
The ! will affect the current array.