Added the six module to test int/long support

mongoengine/fields.py

@@ -8,6 +8,8 @@ import uuid
 import warnings
 from operator import itemgetter
 
+import six
+
 try:
     import dateutil
 except ImportError:
@@ -260,14 +262,14 @@ class FloatField(BaseField):
         return value
 
     def validate(self, value):
-        if isinstance(value, (int, long)):
+        if isinstance(value, six.integer_types):
             try:
                 value = float(value)
             except OverflowError:
                 self.error('The value is too large to be converted to float')
 
         if not isinstance(value, float):
-            self.error('FloatField only accepts float, int and long values')
+            self.error('FloatField only accepts float and integer values')
 
         if self.min_value is not None and value < self.min_value:
             self.error('Float value is too small')