Added Laravel 6.0 support, updated the documentation

Merge pull request orangehill#132 from psadaic/master

add chunksize option

Corrected the wording.

Merge pull request orangehill#107 from megaket4up/laravel5.5autoloadsp

laravel 5.5 support

Merge pull request orangehill#100 from g9308370/add_optional_orderby

add a new optional input  "orderby"

Merge pull request orangehill#98 from orangehill/noindex

Changed --index=0 option to --noindex

Merge pull request orangehill#88 from appstract/laravel-54

Fix typo

Merge pull request orangehill#81 from orangehill/dumpAuto

Implemented composer dump auto-load functionality

Merge pull request orangehill#67 from orangehill/repackSeedDataFix

Fixed repackSeedData() method

Merge pull request orangehill#47 from andjelicsasa/master

prerun/postrun seed events support and PSR-2 code standard