Allow store and state_handler to be passed in from config

[joshcanhelp]

Changes

• Fix a bug that did not allow the configuration file values to be used for user store and state handler
• Fix a type hinting bug that did not allow new state handlers to be passed in
• Add a compatibility scan to CI

References

Closes #154

Testing

• This change adds unit tests
• This change has been tested on PHP 7.1 and Laravel 5.8

[nstapelbroek]

Thanks for taking care 💪

Tested this functionally on my local setup with no configs set to false and that works.

[joshcanhelp]

Added a failed PHP compatibility test for PHP 5.5

9072d6c

> "vendor/bin/phpcs"
.E.......... 12 / 12 (100%)

FILE: src/Auth0/Login/Auth0Service.php
----------------------------------------------------------------------
FOUND 2 ERRORS AFFECTING 2 LINES
----------------------------------------------------------------------
 48 | ERROR | null coalescing operator (??) is not present in PHP
    |       | version 5.6 or earlier
    |       | (PHPCompatibility.PHP.NewLanguageConstructs.t_coalesceFound)
 53 | ERROR | null coalescing operator (??) is not present in PHP
    |       | version 5.6 or earlier
    |       | (PHPCompatibility.PHP.NewLanguageConstructs.t_coalesceFound)
----------------------------------------------------------------------