Use Go1.11 module (#5743)

* Migrate to go modules

* make vendor

* Update mvdan.cc/xurls

* make vendor

* Update code.gitea.io/git

* make fmt-check

* Update github.com/go-sql-driver/mysql

* make vendor

vendor/golang.org/x/oauth2/.travis.yml

@@ -0,0 +1,13 @@
+language: go
+
+go:
+  - tip
+
+install:
+  - export GOPATH="$HOME/gopath"
+  - mkdir -p "$GOPATH/src/golang.org/x"
+  - mv "$TRAVIS_BUILD_DIR" "$GOPATH/src/golang.org/x/oauth2"
+  - go get -v -t -d golang.org/x/oauth2/...
+
+script:
+  - go test -v golang.org/x/oauth2/...

vendor/golang.org/x/oauth2/CONTRIBUTING.md

@@ -0,0 +1,26 @@
+# Contributing to Go
+
+Go is an open source project.
+
+It is the work of hundreds of contributors. We appreciate your help!
+
+## Filing issues
+
+When [filing an issue](https://github.com/golang/oauth2/issues), make sure to answer these five questions:
+
+1.  What version of Go are you using (`go version`)?
+2.  What operating system and processor architecture are you using?
+3.  What did you do?
+4.  What did you expect to see?
+5.  What did you see instead?
+
+General questions should go to the [golang-nuts mailing list](https://groups.google.com/group/golang-nuts) instead of the issue tracker.
+The gophers there will answer or ask you to file an issue if you've tripped over a bug.
+
+## Contributing code
+
+Please read the [Contribution Guidelines](https://golang.org/doc/contribute.html)
+before sending patches.
+
+Unless otherwise noted, the Go source files are distributed under
+the BSD-style license found in the LICENSE file.

vendor/golang.org/x/oauth2/README.md

@@ -0,0 +1,79 @@
+# OAuth2 for Go
+
+[![Build Status](https://travis-ci.org/golang/oauth2.svg?branch=master)](https://travis-ci.org/golang/oauth2)
+[![GoDoc](https://godoc.org/golang.org/x/oauth2?status.svg)](https://godoc.org/golang.org/x/oauth2)
+
+oauth2 package contains a client implementation for OAuth 2.0 spec.
+
+## Installation
+
+~~~~
+go get golang.org/x/oauth2
+~~~~
+
+Or you can manually git clone the repository to
+`$(go env GOPATH)/src/golang.org/x/oauth2`.
+
+See godoc for further documentation and examples.
+
+* [godoc.org/golang.org/x/oauth2](http://godoc.org/golang.org/x/oauth2)
+* [godoc.org/golang.org/x/oauth2/google](http://godoc.org/golang.org/x/oauth2/google)
+
+
+## App Engine
+
+In change 96e89be (March 2015), we removed the `oauth2.Context2` type in favor
+of the [`context.Context`](https://golang.org/x/net/context#Context) type from
+the `golang.org/x/net/context` package. Later replaced by the standard `context` package
+of the [`context.Context`](https://golang.org/pkg/context#Context) type.
+
+
+This means it's no longer possible to use the "Classic App Engine"
+`appengine.Context` type with the `oauth2` package. (You're using
+Classic App Engine if you import the package `"appengine"`.)
+
+To work around this, you may use the new `"google.golang.org/appengine"`
+package. This package has almost the same API as the `"appengine"` package,
+but it can be fetched with `go get` and used on "Managed VMs" and well as
+Classic App Engine.
+
+See the [new `appengine` package's readme](https://github.com/golang/appengine#updating-a-go-app-engine-app)
+for information on updating your app.
+
+If you don't want to update your entire app to use the new App Engine packages,
+you may use both sets of packages in parallel, using only the new packages
+with the `oauth2` package.
+
+```go
+import (
+	"context"
+	"golang.org/x/oauth2"
+	"golang.org/x/oauth2/google"
+	newappengine "google.golang.org/appengine"
+	newurlfetch "google.golang.org/appengine/urlfetch"
+
+	"appengine"
+)
+
+func handler(w http.ResponseWriter, r *http.Request) {
+	var c appengine.Context = appengine.NewContext(r)
+	c.Infof("Logging a message with the old package")
+
+	var ctx context.Context = newappengine.NewContext(r)
+	client := &http.Client{
+		Transport: &oauth2.Transport{
+			Source: google.AppEngineTokenSource(ctx, "scope"),
+			Base:   &newurlfetch.Transport{Context: ctx},
+		},
+	}
+	client.Get("...")
+}
+```
+
+## Report Issues / Send Patches
+
+This repository uses Gerrit for code changes. To learn how to submit changes to
+this repository, see https://golang.org/doc/contribute.html.
+
+The main issue tracker for the oauth2 repository is located at
+https://github.com/golang/oauth2/issues.