Fix failing shortcode tests on Travis

Some newly added shortcode tests compared maps in assertions.

This failed on Travis, as iteration order isn't guaranteed for maps since Go 1.

This commit fixes that by do a sort of the keys in the shortcode String() function.

hugolib/shortcode.go

@@ -21,6 +21,7 @@ import (
 	"html/template"
 	"reflect"
 	"regexp"
+	"sort"
 	"strconv"
 	"strings"
 )
@@ -90,7 +91,28 @@ type shortcode struct {
 
 func (sc shortcode) String() string {
 	// for testing (mostly), so any change here will break tests!
-	return fmt.Sprintf("%s(%q, %t){%s}", sc.name, sc.params, sc.doMarkup, sc.inner)
+	var params interface{}
+	switch v := sc.params.(type) {
+	case map[string]string:
+		// sort the keys so test assertions won't fail
+		var keys []string
+		for k := range v {
+			keys = append(keys, k)
+		}
+		sort.Strings(keys)
+		var tmp = make([]string, len(keys))
+
+		for i, k := range keys {
+			tmp[i] = k + ":" + v[k]
+		}
+		params = tmp
+
+	default:
+		// use it as is
+		params = sc.params
+	}
+
+	return fmt.Sprintf("%s(%q, %t){%s}", sc.name, params, sc.doMarkup, sc.inner)
 }
 
 // all in  one go: extract, render and replace