Moved models to folder, renamed managers to tools

Tools seems to fit better since the classes were a bit of a mixed bunch
and did not always manage.
Also simplified the structure of the SlugGenerator class.
Also focused EntityContext on shelves and simplified to use session
helper.

app/Auth/Access/Guards/ExternalBaseSessionGuard.php

@@ -15,8 +15,6 @@ use Illuminate\Contracts\Session\Session;
  * guard with 'remember' functionality removed. Basic auth and event emission
  * has also been removed to keep this simple. Designed to be extended by external
  * Auth Guards.
- *
- * @package Illuminate\Auth
  */
 class ExternalBaseSessionGuard implements StatefulGuard
 {

app/Auth/Access/Guards/Saml2SessionGuard.php

@@ -9,8 +9,6 @@ namespace BookStack\Auth\Access\Guards;
  * into the default laravel 'Guard' auth flow. Instead most of the logic is done
  * via the Saml2 controller & Saml2Service. This class provides a safer, thin
  * version of SessionGuard.
- *
- * @package BookStack\Auth\Access\Guards
  */
 class Saml2SessionGuard extends ExternalBaseSessionGuard
 {

app/Auth/Access/Ldap.php

@@ -4,7 +4,6 @@
  * Class Ldap
  * An object-orientated thin abstraction wrapper for common PHP LDAP functions.
  * Allows the standard LDAP functions to be mocked for testing.
- * @package BookStack\Services
  */
 class Ldap
 {

app/Auth/SocialAccount.php

@@ -7,7 +7,6 @@ use BookStack\Model;
  * Class SocialAccount
  * @property string $driver
  * @property User $user
- * @package BookStack\Auth
  */
 class SocialAccount extends Model implements Loggable
 {

app/Auth/User.php

@@ -18,7 +18,6 @@ use Illuminate\Notifications\Notifiable;
 
 /**
  * Class User
- * @package BookStack\Auth
  * @property string $id
  * @property string $name
  * @property string $email