Append newlines to ipfs id and ipfs dns output.

This fixes #1083, #2000.

N.B. The JSON package developers see no trailing newline as a feature;
it allows marshalled JSON to be embedded inside more JSON.[0]

--
[0] https://golang.org/pkg/encoding/json/

License: MIT
Signed-off-by: Thomas Gardner <tmg@fastmail.com>

core/commands/id.go

@@ -133,6 +133,7 @@ ipfs id supports the format option for output with the following keys:
 				if err != nil {
 					return nil, err
 				}
+				marshaled = append(marshaled, byte('\n'))
 				return bytes.NewReader(marshaled), nil
 			}
 		},