Port to Laravel 5.5 - Githubissues

Hi,

This is a port to Laravel 5.5 :

Since Laravel 5.5 require PHP >= 7.0, well PHP >= 7.0 is required for this package
So PHPUnit >= 6 is required and testbench 3.5 (for Laravel 5.5)
fire() has been rename to handle()
In Laravel 5.5, there is an "auto discovery" package by adding few lines in composer.json, i just added the service provider (not the facade "Search")
Minor fixes in tests and a typo in phpdoc ;)

Also, this should fix #59 !

If anything is wrong, tell me ;)

Thanks !

nqxcode / laravel-lucene-search