Pre-release 0.1.31

• call_in_background fully refactored, logic moved to helper class;
• Illuminated\Helpers\Artisan\Command added;
• call_in_background fully covered by tests;
• mockery/mockery dev requirement added;
• Mockery integrated to the base class;
• psr-4 composer autoload added for classes;
• src/autoload.php depth set;
• .travis.yml fixes - satooshi/php-coveralls required after install to dev;
• Testsuite name fixed;
• Composer lock updated;