Added IdPAttribute ProcessingFilter

• Added new sspmod_perun_Auth_Process_IdPAttribute filter, which allows to send send attribute from IdPMetadata to SP

config-templates/processFilterConfigurations-example.md

+## IdPAttribute
+
+Example how to enable filter IdPAttribute:
+
+```php
+29 => array(
+        'class' => 'perun:IdPAttribute',
+        'attrMap' => array(
+                'OrganizationName:en' => 'idp_organizationName',
+        ),
+),
+```
+
+'OrganizationName:en' => 'idp_organizationName' means that the $IdPMetadata['Organization']['en'] will be save into 
+$request['Attributes']['idp_organizationName']