refactor: remove request/request http client handling and methods

BREAKING CHANGE: Due to request's maintenance mode and inevitable
deprecation (see request/request#3142)
the option to switch the provider to use request has been removed.

docs/README.md

@@ -519,19 +519,10 @@ property.
 
 
 ## HTTP Request Library / Proxy settings
-By default oidc-provider uses the [got][got-library] module. Because of its lightweight nature of
+oidc-provider uses the [got][got-library] module. Because of its lightweight nature of
 the provider will not use environment-defined http(s) proxies. In order to have them used you'll
-need to require and tell oidc-provider to use [request][request-library] instead.
-
-```sh
-# add request to your application package bundle
-npm install request@^2.0.0 --save
-```
-
-```js
-// tell oidc-provider to use request instead of got
-Provider.useRequest();
-```
+need to follow got's [README](https://github.com/sindresorhus/got#proxies) and use e.g.
+[`global-tunnel`](https://github.com/np-maintain/global-tunnel)
 
 
 ## Changing HTTP Request Defaults

lib/helpers/http/index.js

@@ -7,11 +7,6 @@ const httpWrapper = {
     this.get = got.get;
     this.post = got.post;
   },
-  useRequest() {
-    const request = require('./request'); // eslint-disable-line global-require
-    this.get = request.get;
-    this.post = request.post;
-  },
 };
 
 module.exports = httpWrapper;

lib/provider.js

@@ -353,17 +353,9 @@ class Provider extends events.EventEmitter {
   get DeviceCode() { return instance(this).DeviceCode; }
 
   get requestUriCache() { return instance(this).requestUriCache; }
-
-  static useGot() { // eslint-disable-line class-methods-use-this
-    httpWrapper.useGot();
-  }
-
-  static useRequest() { // eslint-disable-line class-methods-use-this
-    /* istanbul ignore next */
-    httpWrapper.useRequest();
-  }
 }
-Provider.useGot();
+
+httpWrapper.useGot();
 
 ['env', 'proxy', 'subdomainOffset', 'keys'].forEach((method) => {
   Object.defineProperty(Provider.prototype, method, {