align columns

Implement http://rosettacode.org/wiki/Align_columns
I meant that if you change the signature of align_columns to:
`fn align_columns(text: &str) -> (Vec<Vec<String>>, Vec<uint>)` 
then you need to change raw 3 in your main to:
`let (chunks, max_lengths) = align_columns(text.as_slice());`

see the modification [here on the playpen](http://is.gd/BW0N28)