text: Title: Need to push a new version fot DateRangeFilter
  Body: When i saw the doc of this https://github.com/geex-arts/django-jet/blob/master/docs/filters.rst
  
  but my Python raised an error(version: django-jet==1.0.6):
  
  ````python
  from jet.filters import DateRangeFilter
  ImportError: cannot import name 'DateRangeFilter'
  ````
  but it works when i replace ` jet.filters` to `rangefilter.filter` 
  
  should we fix the doc?
  
  ref: https://github.com/geex-arts/django-jet/blob/master/docs/filters.rst
  