Add support for YAML configuration files. Add support for editing setting options and saving them using the new YAML configuration file support. Add new revertsettings management command. Add new permission to edit setting via the UI.

Signed-off-by: Roberto Rosario <roberto.rosario.gonzalez@gmail.com>

mayan/settings/base.py

@@ -11,9 +11,12 @@ https://docs.djangoproject.com/en/1.10/ref/settings/
 """
 from __future__ import unicode_literals
 
+import errno
 import os
 import sys
 
+import yaml
+
 from django.utils.translation import ugettext_lazy as _
 
 import environ
@@ -347,3 +350,44 @@ else:
 # ----- Debug -----
 
 DEBUG = env.bool('MAYAN_DEBUG', default=False)
+
+
+
+CONFIGURATION_FILENAME = '_settings.yml'
+CONFIGURATION_FILEPATH = os.path.join(MEDIA_ROOT, CONFIGURATION_FILENAME)
+
+CONFIGURATION_USER_FILENAME = 'config.yml'
+CONFIGURATION_USER_FILEPATH = os.path.join(
+    MEDIA_ROOT, CONFIGURATION_USER_FILENAME
+)
+
+CONFIGURATION_LAST_GOOD_FILENAME = '_settings_backup.yml'
+CONFIGURATION_LAST_GOOD_FILEPATH = os.path.join(
+    MEDIA_ROOT, CONFIGURATION_LAST_GOOD_FILENAME
+)
+
+
+def read_configuration_file(path):
+    try:
+        with open(CONFIGURATION_FILEPATH) as file_object:
+            file_object.seek(0, os.SEEK_END)
+            if file_object.tell():
+                file_object.seek(0)
+                try:
+                    globals().update(yaml.safe_load(file_object))
+                except yaml.YAMLError as exception:
+                    exit(
+                        'Error loading configuration file: {}; {}'.format(
+                            CONFIGURATION_FILEPATH, exception
+                        )
+                    )
+    except IOError as exception:
+        if exception.errno == errno.ENOENT:
+            pass
+        else:
+            raise
+
+
+if not 'revertsettings' in sys.argv:
+    read_configuration_file(CONFIGURATION_FILEPATH)
+    read_configuration_file(CONFIGURATION_USER_FILEPATH)