Remove Django1.7 shims

[urbandove]

Currently this library says its only compatible for django > 1.8 - this is just removing some shims that were there for earlier version

[coveralls]

Coverage decreased (-0.2%) to 92.953% when pulling d2db5f5 on urbandove:rm-django1.7 into 24706f5 on graphql-python:master.

[coveralls]

Coverage increased (+0.4%) to 93.575% when pulling d2db5f5 on urbandove:rm-django1.7 into 24706f5 on graphql-python:master.

[spockNinja]

Thanks for the cleanup!

We've got an outstanding issue with the Travis build, waiting on #338 so we can get your PR a clean build.

After that, this looks fine to me, and I'll pass it on to the owner. 👍

[coveralls]

Coverage increased (+0.4%) to 93.575% when pulling f31db13 on urbandove:rm-django1.7 into b54e02c on graphql-python:master.