Refactor the converter app

Don't cache the entire converter class to lower memory usage.
Instead a get_converter_class() function is now provided to
load the converter backend class.

Add model permission inheritance to transformations to
removel custom permission checking code in the views.

User keyword arguments.

Update URL parameters to the '_id' form.

Add missing edit and delete icons. Improve the create
icon using composition.

Update add to comply with MERCs 5 and 6.

Signed-off-by: Roberto Rosario <Roberto.Rosario@mayan-edms.com>

mayan/apps/converter/models.py

@@ -60,7 +60,11 @@ class Transformation(models.Model):
         verbose_name_plural = _('Transformations')
 
     def __str__(self):
+        return self.get_transformation_label()
+
+    def get_transformation_label(self):
         return self.get_name_display()
+    get_transformation_label.short_description = _('Name')
 
     def save(self, *args, **kwargs):
         if not self.order: