Move HexTest.scala into Fsq.io
Move HexTest.scala into Fsq.io

Hex.scala was opensourced a little while ago, this
adds the test class.

(sapling split of ce1740a87e7bfebb90aa8effd21957ff96632e45)
foursquare/fsqio,foursquare/fsqio,foursquare/fsqio,foursquare/fsqio,foursquare/fsqio