Refactor update creation api

This merge request does the following:

• Raise DRF errors rather than returning response to take advantage of the DRF exception handling mechanism
• Create serialisers for PUT request to simplify the code
• Improve validation checks in several places
• Fixes several issues in DRF infrastructure uses
• Fixes JSON fields handling
• Remove routes that do no fully qualify objects
• Implement a custom DRF exception handler that will allow to log errors
• Improve testing
• Improve permission management

beat/web/common/fields.py

@@ -26,21 +26,7 @@
 ###############################################################################
 
 from rest_framework import serializers
-from django.utils import six
-
-import simplejson
 
 
 class StringListField(serializers.ListField):
     child = serializers.CharField()
-
-
-class JSONSerializerField(serializers.Field):
-    """ Serializer for JSONField -- required to make field writable"""
-    def to_internal_value(self, data):
-        if isinstance(data, six.string_types):
-            return simplejson.loads(data)
-        return data
-
-    def to_representation(self, value):
-        return value