Move YAML code to its own module

Code now resides in common.serialization in the form
of two new functions: yaml_load and yaml_dump.

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

mayan/apps/smart_settings/classes.py

@@ -9,11 +9,6 @@ import sys
 
 import yaml
 
-try:
-    from yaml import CSafeLoader as SafeLoader, CSafeDumper as SafeDumper
-except ImportError:
-    from yaml import SafeLoader, SafeDumper
-
 from django.apps import apps
 from django.conf import settings
 from django.utils.functional import Promise
@@ -21,6 +16,8 @@ from django.utils.encoding import (
     force_bytes, force_text, python_2_unicode_compatible
 )
 
+from mayan.apps.common.serialization import yaml_dump, yaml_load
+
 logger = logging.getLogger(__name__)
 
 
@@ -85,7 +82,7 @@ class Setting(object):
 
     @staticmethod
     def deserialize_value(value):
-        return yaml.load(stream=value, Loader=SafeLoader)
+        return yaml_load(stream=value)
 
     @staticmethod
     def express_promises(value):
@@ -101,9 +98,8 @@ class Setting(object):
 
     @staticmethod
     def serialize_value(value):
-        result = yaml.dump(
+        result = yaml_dump(
             data=Setting.express_promises(value), allow_unicode=True,
-            Dumper=SafeDumper
         )
         # safe_dump returns bytestrings
         # Disregard the last 3 dots that mark the end of the YAML document
@@ -128,8 +124,8 @@ class Setting(object):
                 if (filter_term and filter_term.lower() in setting.global_name.lower()) or not filter_term:
                     dictionary[setting.global_name] = Setting.express_promises(setting.value)
 
-        return yaml.dump(
-            data=dictionary, default_flow_style=False, Dumper=SafeDumper
+        return yaml_dump(
+            data=dictionary, default_flow_style=False
         )
 
     @classmethod