Hopefully this saves time for new users of django-configuration (like myself), who "just needed" to lazily evaluate a string inside a dictionary.
This doubles as an example for `RAVEN_CONFIG` which was the whole reason I was here in the first place... The actual problem I faced was that a setting remains of type `values.Value` when nested inside a dictionary. Which results in a weird issues like this:
```
2018-02-24T20:59:26.125208+00:00 app[web.1]: Traceback (most recent call last):
2018-02-24T20:59:26.125364+00:00 app[web.1]: self.client.http_context(self.get_http_context(environ))
2018-02-24T20:59:26.125215+00:00 app[web.1]: File "/app/.heroku/python/lib/python3.6/site-packages/raven/middleware.py", line 98, in __call__
2018-02-24T20:59:26.125368+00:00 app[web.1]: File "/app/.heroku/python/lib/python3.6/site-packages/raven/contrib/django/models.py", line 54, in <lambda>
2018-02-24T20:59:26.125482+00:00 app[web.1]: __getattr__ = lambda x, o: getattr(get_client(), o)
2018-02-24T20:59:26.125486+00:00 app[web.1]: File "/app/.heroku/python/lib/python3.6/site-packages/raven/contrib/django/models.py", line 134, in get_client
2018-02-24T20:59:26.125613+00:00 app[web.1]: instance = Client(**options)
2018-02-24T20:59:26.125618+00:00 app[web.1]: File "/app/.heroku/python/lib/python3.6/site-packages/raven/contrib/django/client.py", line 147, in __init__
2018-02-24T20:59:26.125769+00:00 app[web.1]: Client.__init__(self, *args, **kwargs)
2018-02-24T20:59:26.125771+00:00 app[web.1]: File "/app/.heroku/python/lib/python3.6/site-packages/raven/base.py", line 171, in __init__
2018-02-24T20:59:26.125927+00:00 app[web.1]: self.set_dsn(dsn, transport)
2018-02-24T20:59:26.125929+00:00 app[web.1]: File "/app/.heroku/python/lib/python3.6/site-packages/raven/base.py", line 251, in set_dsn
2018-02-24T20:59:26.126063+00:00 app[web.1]: if dsn not in self._transport_cache:
2018-02-24T20:59:26.126076+00:00 app[web.1]: TypeError: unhashable type: 'Value'
```
- Drop django==1.9 as it reached end of life
- Drop python2.6, python3.3, and bring python3.6
- Bring django-2.0 in the matrix as expected failure until we add its
support
As per [their blog post of the 27th April](https://blog.readthedocs.com/securing-subdomains/) ‘Securing subdomains’:
> Starting today, Read the Docs will start hosting projects from subdomains on the domain readthedocs.io, instead of on readthedocs.org. This change addresses some security concerns around site cookies while hosting user generated data on the same domain as our dashboard.
Test Plan: Manually visited all the links I’ve modified.
It's better to try the new import method first because in Django<1.9 the
old method is still available and will raise a RemovedInDjango19Warning
that we could have avoided.
