Implement git refs API for listing references (branches, tags and other) (#5354)

* Inital routes to git refs api

* Git refs API implementation

* Update swagger

* Fix copyright

* Make swagger happy add basic test

* Fix test

* Fix test again :)

vendor/gopkg.in/src-d/go-git.v4/utils/diff/diff.go

@@ -0,0 +1,45 @@
+// Package diff implements line oriented diffs, similar to the ancient
+// Unix diff command.
+//
+// The current implementation is just a wrapper around Sergi's
+// go-diff/diffmatchpatch library, which is a go port of Neil
+// Fraser's google-diff-match-patch code
+package diff
+
+import (
+	"bytes"
+
+	"github.com/sergi/go-diff/diffmatchpatch"
+)
+
+// Do computes the (line oriented) modifications needed to turn the src
+// string into the dst string.
+func Do(src, dst string) (diffs []diffmatchpatch.Diff) {
+	dmp := diffmatchpatch.New()
+	wSrc, wDst, warray := dmp.DiffLinesToRunes(src, dst)
+	diffs = dmp.DiffMainRunes(wSrc, wDst, false)
+	diffs = dmp.DiffCharsToLines(diffs, warray)
+	return diffs
+}
+
+// Dst computes and returns the destination text.
+func Dst(diffs []diffmatchpatch.Diff) string {
+	var text bytes.Buffer
+	for _, d := range diffs {
+		if d.Type != diffmatchpatch.DiffDelete {
+			text.WriteString(d.Text)
+		}
+	}
+	return text.String()
+}
+
+// Src computes and returns the source text
+func Src(diffs []diffmatchpatch.Diff) string {
+	var text bytes.Buffer
+	for _, d := range diffs {
+		if d.Type != diffmatchpatch.DiffInsert {
+			text.WriteString(d.Text)
+		}
+	}
+	return text.String()
+}