Set Go distribution to 1.8
Set Go distribution to 1.8

If we need 1.8.1 we will need to ship that binary
to upstream Pants.

(sapling split of a0b3966341f5bd65a48a80f7643f0835796dcf2f)
foursquare/fsqio,foursquare/fsqio,foursquare/fsqio,foursquare/fsqio,foursquare/fsqio