Rpc4django

- Fix deprecation warnings

- Django 2.* support

- Improve support for PEP3107 function annotations
- Add multicall support
- request argument is now provided explicitly

- Preliminary support for PEP3107 function annotations (`43`_)
- Modifications for compatibility with Django 1.8-1.11 (`49`_)
- Fixes for unexpected content types (`47`_)
- Fixes for JSONRPC 2.0 spec (`32`_)
- Drop support for Django before 1.8 (follow Django project supported versions)

Thanks to all those who helped out!

.. _32: https://github.com/rpc4django/rpc4django/issues/32
.. _43: https://github.com/rpc4django/rpc4django/pull/43
.. _47: https://github.com/rpc4django/rpc4django/pull/47
.. _49: https://github.com/rpc4django/rpc4django/pull/49

- Use the defusedxml library for XML parsing and XMLRPC which solves
issues with entity expansion. Thanks to Dan Burrowes for reporting the
issues.
- Fix a bug involving unicode literals causing TypeErrors (`31`_)

.. _31: https://github.com/davidfischer/rpc4django/pull/31

- Django 1.6 compatibility (`29`_)

.. _29: https://github.com/davidfischer/rpc4django/pull/29