Basic Proxy model support

[jm2242]

This PR, in reference to #319 :

• adds support for querying a table that has proxy model representations in Django, as long as the type is declared to be the superclass (and not the proxy model class). While you could still query for all objects of a particular type, if those objects were cast to a proxy model at runtime, the is_type_of() for the object would fail.
  - adds on_delete where it was breaking tests due to Django 2 requirement
• fixes tests associated with the Reporter model, to accommodate an additional field reporter_type

In the future, a more intentional way of dealing with Proxy models can be considered.

There are 4 failing tests that are unrelated to this PR

[coveralls]

Coverage remained the same at 93.142% when pulling 3c1f67f on jm2242:proxy-model-support into b54e02c on graphql-python:master.

[coveralls]

Coverage remained the same at 93.142% when pulling 3c1f67f on jm2242:proxy-model-support into b54e02c on graphql-python:master.

[coveralls]

Coverage remained the same at 93.142% when pulling 3c1f67f on jm2242:proxy-model-support into b54e02c on graphql-python:master.

[coveralls]

Coverage remained the same at 94.203% when pulling bfcfccf on jm2242:proxy-model-support into e827b10 on graphql-python:master.

[patrick91]

Looks good to me, I just commented two things about code style.

Since I'm not familiar with proxy models, maybe it would be worth having a review from @mjtamlyn and @spockNinja if they have some time :)

EDIT: if you rebase from master the failing on the CI should disappear :)

[patrick91]

nit: can you add a line break before the closing )? just to be consistent with the rest of the changes

[patrick91]

nit: can you add a space before and after the =?

[jm2242]

@patrick91 rebased and made the style changes (hopefully I understood the first one)

[patrick91]

@jm2242 I mean a line break, like this:

...
    choices=[(1, u'Regular'), (2, u'CNN Reporter')]
)

[jm2242]

that was silly, fixed

[spockNinja]

Thanks for the PR!

The changes for proxy model support look great.

There is a separate PR dealing with Django 2.0 test support (#336), so if you would slim this PR down to just the proxy model changes and tests, that would be great, and we'll move this PR forward.

Thanks again!

[jm2242]

no problem @spockNinja, done!

[mjtamlyn]

To be honest I know next to nothing about proxy models so probably can't help much here :)

[syrusakbary]

The PR looks good, merging :)
Thanks for the reviews @spockNinja @patrick91 @mjtamlyn

[serates]

Is graphene-django looking to release a new version and release this to pypi, the last build released was in october. I would like to have access to this fix so that i no longer have to use chain and lists for some of my queries that need proxy support