Improvement on install command

[jiaojie1989]

In file https://github.com/Laravel-Backpack/FileManager/blob/master/src/Console/Commands/Install.php line 59

        $this->line(' Publishing elFinder assets');
        $this->executeProcess(['php', 'artisan', 'elfinder:publish']);

It's better use executeArtisanProcess instead of executeProcess, for there exists differences between environments of users, the command php may refer to another bin file than the running one.

Improvement:

        $this->executeArtisanProcess('elfinder:publish');

[promatik]

Thank you for the heads up @jiaojie1989 🙌

I've integrated that change on https://github.com/Laravel-Backpack/FileManager/pull/25/files#diff-5edc8f1b571acbaf0d8d72484f20e346177a145de58e48e1f354ba786bf2574fR59