Update changelog

Merge pull request thephpleague#970 from Sephster/interface-revert

Revert Interface Change

Update changelog for 7.3.0 release

Update for version 7.2.0

Merge pull request thephpleague#918 from Sephster/fix-914

Fix empty issue in PHP 5.4

Add PR reference

Update changelog for version 7.1.0

Merge pull request thephpleague#854 from Sephster/master

Version 7

Update AbstractGrant.php

Temporarily removing check on empty scopes as causing issues for Passport users

Update README.md

Updating readme to refer to the latest 5.1.* branch