Update go dep (#1560)

This fix updates go dep with `dep ensure --update` as well as the following:
- Removed github.com/ugorji/go restriction in Gopkg.toml (fixes  #1557)
- Added github.com/flynn/go-shlex in Makefile (neede by Caddy, maybe removed later)

This fix fixes #1557

Signed-off-by: Yong Tang <yong.tang.github@outlook.com>

vendor/github.com/farsightsec/golang-framestream/Encoder.go

@@ -68,7 +68,7 @@ func NewEncoder(w io.Writer, opt *EncoderOptions) (enc *Encoder, err error) {
 	// Write the start control frame.
 	start := ControlStart
 	start.SetContentType(opt.ContentType)
-	err = start.Encode(enc.writer)
+	err = start.EncodeFlush(enc.writer)
 	if err != nil {
 		return
 	}