Improve how settings are loaded from config file

Update the way settings are loaded. Instead of loading the
entire config file now settings are loaded from the config
file on demand when the cache misses.

Improve the smart settings classes tests and add another test
for the config file loading.

Add support for variable config file path.

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

mayan/apps/smart_settings/classes.py

@@ -13,6 +13,8 @@ from django.conf import settings
 from django.utils.functional import Promise
 from django.utils.encoding import force_text, python_2_unicode_compatible
 
+from .utils import read_configuration_file
+
 logger = logging.getLogger(__name__)
 
 
@@ -173,7 +175,13 @@ class Setting(object):
                     )
                 )
         else:
-            self.raw_value = getattr(settings, self.global_name, self.default)
+            self.raw_value = read_configuration_file(
+                path=settings.CONFIGURATION_FILEPATH
+            ).get(
+                self.global_name, getattr(
+                    settings, self.global_name, self.default
+                )
+            )
 
         self.yaml = Setting.serialize_value(self.raw_value)
         self.loaded = True