Updated README.md
Updated README.md

Updated the README.md file to reflect configurations changes necessary with Laravel 5.1, specifically:

- Newer ::class formats for providers and aliases
- Updated the provider example to use the newer array syntax and ensure it matches the code base.
- For my installation the provider list and dataper had to start with a \ character or I received errors. This was a difficult error to spot and could easily trip up new users.
geocoder-php/GeocoderLaravel