Add Django 2 support and update other dependencies.

[kblicharski]

Changes

• django.core.urlresolvers import reverse became from django.urls import reverse
• user.is_authenticated() became user.is_authenticated
• MIDDLEWARE_CLASSES became MIDDLEWARE
• on_delete kwarg was added to all ForeignKeys/OneToOneFields/etc
• All dependencies were updated to their most recent versions

I also added pip-review and pipdeptree as dev dependencies and reformatted the code to remove unused imports and add/remove newlines as needed.

[coveralls]

Coverage decreased (-8.9%) to 88.571% when pulling 3e79f7a on thesignalcenter:master into 8928bc9 on orcasgit:master.

[kblicharski]

The CI jobs are all failing due to supporting Django 1.9 and lower. I'm not sure how to add this feature while still retaining backwards compatibility for these versions of Django, so if the maintainers of this repository are still active, it's up to them whether it's worth deprecating and removing Django versions 1.8 and 1.9.

[rahul003]

@kblicharski Has the source branch for this PR been removed? I would like to fetch it and merge locally since the PR doesn't seem to be going into this repo.

[rahul003]

Ah never mind, just noticed that the account was not @kblicharski , but rather @thesignalcenter

[brad]

@rahul003 You're right, this PR will not be merged in. We will add 2.0 support without all the other extra changes this PR includes