Update import paths from github.com/go-gitea to code.gitea.io (#135)

- Update import paths from github.com/go-gitea to code.gitea.io
- Fix import path for travis

See https://docs.travis-ci.com/user/languages/go#Go-Import-Path

vendor/code.gitea.io/git/submodule.go

@@ -0,0 +1,78 @@
+// Copyright 2015 The Gogs 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"
+
+type SubModule struct {
+	Name string
+	URL  string
+}
+
+// SubModuleFile represents a file with submodule type.
+type SubModuleFile struct {
+	*Commit
+
+	refURL string
+	refID  string
+}
+
+func NewSubModuleFile(c *Commit, refURL, refID string) *SubModuleFile {
+	return &SubModuleFile{
+		Commit: c,
+		refURL: refURL,
+		refID:  refID,
+	}
+}
+
+// RefURL guesses and returns reference URL.
+func (sf *SubModuleFile) RefURL(urlPrefix string, parentPath string) string {
+	if sf.refURL == "" {
+		return ""
+	}
+
+	url := strings.TrimSuffix(sf.refURL, ".git")
+
+	// git://xxx/user/repo
+	if strings.HasPrefix(url, "git://") {
+		return "http://" + strings.TrimPrefix(url, "git://")
+	}
+
+	// http[s]://xxx/user/repo
+	if strings.HasPrefix(url, "http://") || strings.HasPrefix(url, "https://") {
+		return url
+	}
+
+	// Relative url prefix check (according to git submodule documentation)
+	if strings.HasPrefix(url, "./") || strings.HasPrefix(url, "../") {
+		// ...construct and return correct submodule url here...
+		idx := strings.Index(parentPath, "/src/")
+		if idx == -1 {
+			return url
+		}
+		return strings.TrimSuffix(urlPrefix, "/") + parentPath[:idx] + "/" + url
+	}
+
+	// sysuser@xxx:user/repo
+	i := strings.Index(url, "@")
+	j := strings.LastIndex(url, ":")
+
+	// Only process when i < j because git+ssh://git@git.forwardbias.in/npploader.git
+	if i > -1 && j > -1 && i < j {
+		// fix problem with reverse proxy works only with local server
+		if strings.Contains(urlPrefix, url[i+1:j]) {
+			return urlPrefix + url[j+1:]
+		} else {
+			return "http://" + url[i+1:j] + "/" + url[j+1:]
+		}
+	}
+
+	return url
+}
+
+// RefID returns reference ID.
+func (sf *SubModuleFile) RefID() string {
+	return sf.refID
+}