v0.3.0

• Rewritten from scratch, introduced new API to add support for new backends and partition types
• All default model settings which are done inside model's Meta class are now set to None, that means
  that there are no more default settings. Everything should be explicitly defined inside each model class.
• Introduced new model setting partition_type which currently accepts only one value range
• Introduced new model setting partition_subtype which currently accepts only one value date and
  is used only with partition_type when it's set to range
• Better error handling, django-db-parti tries it's best to tell you where and why an error occured
• Added support for day and year partitioning for all backends in addition to week and month
• PostgreSQL: new partitions are now created at the database level, that gave some speed improvement,
  also we don't rely on Django's save() method anymore, that means that there is no more limitation
  with Django's bulk_create() method, you can use it freely with partitioned tables
• PostgreSQL: fixed an error when last day of the week or month wasn't inserted into partition