cmd/getgo: have consistent messages

Currently, we output:

The latest go version is go1.8.3, install that? Y/n [Y]: Y
Download go version go1.8.3 to /Users/jbd/.go? Y/n [Y]: Y

Change-Id: I4fa72f2066259b75d3349487dae5bdced9fdd8a2
Reviewed-on: https://go-review.googlesource.com/51910
Reviewed-by: Chris Broadfoot <cbro@golang.org>
1 file changed