go vet yourself (#397)

go vet caught some nifty bugs. so fixed those here, and also made it so that
we vet everything from now on since the robots seem to do a better job of
vetting than we have managed to.

also adds gofmt check to circle. could move this to the test.sh script (didn't
want a script calling a script, because $reasons) and it's nice and isolated
in its own little land as it is. side note, changed the script so it runs in
100ms instead of 3s, i think find is a lot faster than go list.

attempted some minor cleanup of various scripts

examples/tutorial/hello/go/func.go

@@ -22,6 +22,6 @@ func main() {
 	log.Println("---> stderr goes to the server logs.")
 	log.Println("---> LINE 2")
 	log.Println("---> LINE 3 with a break right here\nand LINE 4")
-	log.Println("---> LINE 5 with a double line break\n")
+	log.Printf("---> LINE 5 with a double line break\n\n")
 	log.Println("---> LINE 6")
 }