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/go-openapi/swag/loading.go

@@ -19,6 +19,7 @@ import (
 	"io/ioutil"
 	"log"
 	"net/http"
+	"net/url"
 	"path/filepath"
 	"strings"
 	"time"
@@ -43,7 +44,10 @@ func LoadStrategy(path string, local, remote func(string) ([]byte, error)) func(
 	if strings.HasPrefix(path, "http") {
 		return remote
 	}
-	return func(pth string) ([]byte, error) { return local(filepath.FromSlash(pth)) }
+	return func(pth string) ([]byte, error) {
+		upth, _ := url.PathUnescape(pth)
+		return local(filepath.FromSlash(upth))
+	}
 }
 
 func loadHTTPBytes(timeout time.Duration) func(path string) ([]byte, error) {