FIX compatibility with Laravel 6.8 (babenkoivan#307)

Remove -s option for searchable model generation to fix compatibility with laravel 6.8

* Fixed bootSearchable to be executed only once

* Fixed Elsaticsearch compatibility issue

ES7 support

ES7 support was reverted as it's not back compatible and must be rele…

…ase as a new v4 version.

* ES 7 support

* Scout Key support
* Spatial relation in geo shape query
* Bug fixes

Scout 7 support

Fixed an issue, when shouldBeSearchable method was used

Scout 6 support

Bug fixes

Fixed document payload zero key issue