Add functionality to support multiple directories

[lchris44]

Summary of the change:

Added option to support multiple directories.

You will be able to achieve that by publishing the LfmConfigHandler and defining a function with the name userAuthDirs()

Inside that function, you can return an array with the user authorized working directories.

Important note: In order to make this work you need to set the userField as '/' like in the example below.

Example:

class LfmConfigHandler
 {
     public function userField()
     {
         return '/';
     }

     public function userAuthDirs()
     {   
         // this will return for example ['files/department1', 'files/department4']
         return Auth::user()->departmentsDirNames();
     }
 }