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/code.gitea.io/git/repo_ref.go

@@ -0,0 +1,51 @@
+// Copyright 2018 The Gitea Authors. All rights reserved.
+// Use of this source code is governed by a MIT-style
+// license that can be found in the LICENSE file.
+
+package git
+
+import (
+	"strings"
+
+	"gopkg.in/src-d/go-git.v4"
+	"gopkg.in/src-d/go-git.v4/plumbing"
+)
+
+// GetRefs returns all references of the repository.
+func (repo *Repository) GetRefs() ([]*Reference, error) {
+	return repo.GetRefsFiltered("")
+}
+
+// GetRefsFiltered returns all references of the repository that matches patterm exactly or starting with.
+func (repo *Repository) GetRefsFiltered(pattern string) ([]*Reference, error) {
+	r, err := git.PlainOpen(repo.Path)
+	if err != nil {
+		return nil, err
+	}
+
+	refsIter, err := r.References()
+	if err != nil {
+		return nil, err
+	}
+	refs := make([]*Reference, 0)
+	if err = refsIter.ForEach(func(ref *plumbing.Reference) error {
+		if ref.Name() != plumbing.HEAD && !ref.Name().IsRemote() &&
+			(pattern == "" || strings.HasPrefix(ref.Name().String(), pattern)) {
+			r := &Reference{
+				Name:   ref.Name().String(),
+				Object: SHA1(ref.Hash()),
+				Type:   string(ObjectCommit),
+				repo:   repo,
+			}
+			if ref.Name().IsTag() {
+				r.Type = string(ObjectTag)
+			}
+			refs = append(refs, r)
+		}
+		return nil
+	}); err != nil {
+		return nil, err
+	}
+
+	return refs, nil
+}