Improve migrations to support migrating milestones/labels/issues/comments/pullrequests (#6290)

* add migrations

* fix package dependency

* fix lints

* implements migrations except pull requests

* add releases

* migrating releases

* fix bug

* fix lint

* fix migrate releases

* fix tests

* add rollback

* pull request migtations

* fix import

* fix go module vendor

* add tests for upload to gitea

* more migrate options

* fix swagger-check

* fix misspell

* add options on migration UI

* fix log error

* improve UI options on migrating

* add support for username password when migrating from github

* fix tests

* remove comments and fix migrate limitation

* improve error handles

* migrate API will also support migrate milestones/labels/issues/pulls/releases

* fix tests and remove unused codes

* add DownloaderFactory and docs about how to create a new Downloader

* fix misspell

* fix migration docs

* Add hints about migrate options on migration page

* fix tests

vendor/github.com/google/go-github/v24/github/licenses.go

@@ -0,0 +1,97 @@
+// Copyright 2013 The go-github AUTHORS. All rights reserved.
+//
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package github
+
+import (
+	"context"
+	"fmt"
+)
+
+// LicensesService handles communication with the license related
+// methods of the GitHub API.
+//
+// GitHub API docs: https://developer.github.com/v3/licenses/
+type LicensesService service
+
+// RepositoryLicense represents the license for a repository.
+type RepositoryLicense struct {
+	Name *string `json:"name,omitempty"`
+	Path *string `json:"path,omitempty"`
+
+	SHA         *string  `json:"sha,omitempty"`
+	Size        *int     `json:"size,omitempty"`
+	URL         *string  `json:"url,omitempty"`
+	HTMLURL     *string  `json:"html_url,omitempty"`
+	GitURL      *string  `json:"git_url,omitempty"`
+	DownloadURL *string  `json:"download_url,omitempty"`
+	Type        *string  `json:"type,omitempty"`
+	Content     *string  `json:"content,omitempty"`
+	Encoding    *string  `json:"encoding,omitempty"`
+	License     *License `json:"license,omitempty"`
+}
+
+func (l RepositoryLicense) String() string {
+	return Stringify(l)
+}
+
+// License represents an open source license.
+type License struct {
+	Key  *string `json:"key,omitempty"`
+	Name *string `json:"name,omitempty"`
+	URL  *string `json:"url,omitempty"`
+
+	SPDXID         *string   `json:"spdx_id,omitempty"`
+	HTMLURL        *string   `json:"html_url,omitempty"`
+	Featured       *bool     `json:"featured,omitempty"`
+	Description    *string   `json:"description,omitempty"`
+	Implementation *string   `json:"implementation,omitempty"`
+	Permissions    *[]string `json:"permissions,omitempty"`
+	Conditions     *[]string `json:"conditions,omitempty"`
+	Limitations    *[]string `json:"limitations,omitempty"`
+	Body           *string   `json:"body,omitempty"`
+}
+
+func (l License) String() string {
+	return Stringify(l)
+}
+
+// List popular open source licenses.
+//
+// GitHub API docs: https://developer.github.com/v3/licenses/#list-all-licenses
+func (s *LicensesService) List(ctx context.Context) ([]*License, *Response, error) {
+	req, err := s.client.NewRequest("GET", "licenses", nil)
+	if err != nil {
+		return nil, nil, err
+	}
+
+	var licenses []*License
+	resp, err := s.client.Do(ctx, req, &licenses)
+	if err != nil {
+		return nil, resp, err
+	}
+
+	return licenses, resp, nil
+}
+
+// Get extended metadata for one license.
+//
+// GitHub API docs: https://developer.github.com/v3/licenses/#get-an-individual-license
+func (s *LicensesService) Get(ctx context.Context, licenseName string) (*License, *Response, error) {
+	u := fmt.Sprintf("licenses/%s", licenseName)
+
+	req, err := s.client.NewRequest("GET", u, nil)
+	if err != nil {
+		return nil, nil, err
+	}
+
+	license := new(License)
+	resp, err := s.client.Do(ctx, req, license)
+	if err != nil {
+		return nil, resp, err
+	}
+
+	return license, resp, nil
+}