[BREAKING CHANGE] Remove preq from library

Remove preq from library entirely and
replace with native fetch.

This is not backwards compatible if third
party users are a) using the parseAll function,
and b) other features of preq, such as
the internalUri parameter or wrapped errors;
see https://github.com/wikimedia/preq for more
details on how preq alters the Response
object.

Bug: T361602

Author: mvolz

README.md

@@ -42,12 +42,11 @@ The scrape method used here invokes the parseAll() method, which uses all the av
 Promise-based:
 ```js
 var cheerio = require('cheerio');
-var preq = require('preq'); // Promisified request library
 var parseDublinCore = require('html-metadata').parseDublinCore;
 
 var url = "http://blog.woorank.com/2013/04/dublin-core-metadata-for-seo-and-usability/";
 
-preq(url).then(function(response){
+fetch(url).then(function(response){
 	$ = cheerio.load(response.body);
 	return parseDublinCore($).then(function(metadata){
 		console.log(metadata);

index.js

@@ -12,7 +12,6 @@ Import modules
  */
 const BBPromise = require( 'bluebird' );
 const cheerio = require( 'cheerio' );
-const preq = require( 'preq' ); // Promisified Request library
 const fs = BBPromise.promisifyAll( require( 'fs' ) );
 
 const index = require( './lib/index.js' );
@@ -27,8 +26,27 @@ const index = require( './lib/index.js' );
  * @return {Object}              BBPromise for metadata
  */
 exports = module.exports = function ( urlOrOpts, callback ) {
-	return preq.get( urlOrOpts
-	).then( ( response ) => index.parseAll( cheerio.load( response.body ) ) ).nodeify( callback );
+	let url, opts;
+	if ( urlOrOpts instanceof Object ) {
+		if ( urlOrOpts.uri ) {
+			url = urlOrOpts.uri;
+		}
+		opts = urlOrOpts;
+	} else if ( typeof urlOrOpts === String ) {
+		url = urlOrOpts;
+	}
+	if ( !url ) {
+		return BBPromise.reject( 'No uri supplied in argument' ).nodeify( callback );
+	} else {
+		return BBPromise.resolve(
+			fetch( url, opts ).then( ( response ) => {
+				// todo check if either urloropts still works with fetch
+				return response.text().then( ( body ) => {
+					return index.parseAll( cheerio.load( body ) );
+				} );
+			} )
+		).nodeify( callback );
+	}
 };
 
 /**