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

api/agent/func_logger.go

@@ -185,7 +185,7 @@ func (l *limitWriter) Write(b []byte) (int, error) {
 	l.n += n
 	if l.n >= l.max {
 		// write in truncation message to log once
-		l.Writer.Write([]byte(fmt.Sprintf("\n-----max log size %d bytes exceeded, truncating log-----\n")))
+		l.Writer.Write([]byte(fmt.Sprintf("\n-----max log size %d bytes exceeded, truncating log-----\n", l.max)))
 	}
 	return n, err
 }