Added default value of `null` to the property argument in the Collection#random method
Moved logic for parsing a php file from the Base loader into a Php parser class
Reran php-cs-fixer over tests directory
Created Yaml parser class, and in doing so, created a Base parser class and tests around the Php parser
Created new Loader class from old Base loader class and implemented it in the Fixtures class
Moved existing tests for the Base and Yaml loaders to the Loader and Yaml parser test files
Added ability to add parsers to the Loader class, and wrote an example CSV parser to display simplicity of the extension
Moved objects injection into processors from the constructor to a setter