README: drop outdated info, simplify install (#645)

* README: drop outdated info, simplify install

* README: remove tagging

Author: Tomáš Votruba

README.md

@@ -1,12 +1,4 @@
-# PHP GitHub API 2.0
-
-In 2.0 lib no longer uses guzzle 3.7, instead it has an HTTPlug abstraction layer. 
-
-For old version please check:
-
-* [branch](https://github.com/KnpLabs/php-github-api/tree/1.7)
-* [readme](https://github.com/KnpLabs/php-github-api/tree/1.7/README.md)
-* [docs](https://github.com/KnpLabs/php-github-api/tree/1.7/doc)
+# PHP GitHub API
 
 [![Build Status](https://travis-ci.org/KnpLabs/php-github-api.svg?branch=master)](https://travis-ci.org/KnpLabs/php-github-api)
 [![StyleCI](https://styleci.io/repos/3948501/shield?style=flat)](https://styleci.io/repos/3948501)
@@ -17,7 +9,6 @@ Uses [GitHub API v3](http://developer.github.com/v3/) & supports [GitHub API v4]
 
 ## Features
 
-* Follows PSR-4 conventions and coding standard: autoload friendly
 * Light and fast thanks to lazy loading of API classes
 * Extensively tested and documented
 
@@ -29,20 +20,15 @@ Uses [GitHub API v3](http://developer.github.com/v3/) & supports [GitHub API v4]
 
 ## Install
 
-The new version of `php-github-api` using [Composer](http://getcomposer.org).
-The first step to use `php-github-api` is to download composer:
+Via Composer:
 
 ```bash
-$ curl -s http://getcomposer.org/installer | php
-```
-
-Then run the following command to require the library:
-```bash
-$ php composer.phar require knplabs/github-api php-http/guzzle6-adapter
+$ composer require knplabs/github-api php-http/guzzle6-adapter
 ```
 
 Why `php-http/guzzle6-adapter`? We are decoupled from any HTTP messaging client with help by [HTTPlug](http://httplug.io/). Read about clients in our [docs](doc/customize.md).
 
+
 ## Using Laravel?
 
 [Laravel GitHub](https://github.com/GrahamCampbell/Laravel-GitHub) by [Graham Campbell](https://github.com/GrahamCampbell) might interest you.
@@ -53,7 +39,7 @@ Why `php-http/guzzle6-adapter`? We are decoupled from any HTTP messaging client
 <?php
 
 // This file is generated by Composer
-require_once 'vendor/autoload.php';
+require_once __DIR__ . '/vendor/autoload.php';
 
 $client = new \Github\Client();
 $repositories = $client->api('user')->repositories('ornicar');
@@ -69,7 +55,7 @@ This example uses the PSR6 cache pool [redis-adapter](https://github.com/php-cac
 <?php
 
 // This file is generated by Composer
-require_once 'vendor/autoload.php';
+require_once __DIR__ . '/vendor/autoload.php';
 
 use Cache\Adapter\Redis\RedisCachePool;