Refresh token not issued using Implicit and Client Credentials grant types

This commit fixes bug #21.
Now refresh token are not issued using Implicit and Client Credentials
grant types (thanks to @jeffxpx).
Merge pull request #68 from Spomky/master

Refresh token not issued using Implicit and Client Credentials grant types
PSR-0 to PSR-4 Autoloading

* PSR-0 => PSR-4
* PHP 5.6 tests added
* PHPUnit 4.x used instead of the version used by Travis-CI
* HHVM test badge added
Merge pull request #70 from Spomky/master

Structural changes
Changed the travis config to use the builtin composer
bootstrap.php removed

Now `vendor/autoload.php` is used directly.
Merge pull request #71 from Spomky/master

bootstrap.php removed
Fixed wrong scope(s) associated to accessToken

Conflicts:
	lib/OAuth2/OAuth2.php
Merge pull request #64 from pyrech/patch-1

Use scope asked by the client if any