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/forms.py

@@ -2,15 +2,12 @@ from __future__ import unicode_literals
 
 import yaml
 
-try:
-    from yaml import CSafeLoader as SafeLoader
-except ImportError:
-    from yaml import SafeLoader
-
 from django import forms
 from django.core.exceptions import ValidationError
 from django.utils.translation import ugettext_lazy as _
 
+from mayan.apps.common.serialization import yaml_load
+
 
 class SettingForm(forms.Form):
     value = forms.CharField(
@@ -38,7 +35,7 @@ class SettingForm(forms.Form):
                 )
 
         try:
-            yaml.load(stream=self.cleaned_data['value'], Loader=SafeLoader)
+            yaml_load(stream=self.cleaned_data['value'])
         except yaml.YAMLError:
             raise ValidationError(
                 _(