Django2

[sheagcraig]

This pull request updates a number of minor things that are API changes between django 1.10 and django 1.11+ (we're going straight to the current release, which is django 2.1.4).

At this time, I also updated a number of other dependency packages to ensure we got versions that were compatible with newer django versions.

The changes are mostly summarized thusly:

• All ForeignKey relationships now require an explicit on_delete parameter. They have all been set to models.CASCADE which is the existing behavior; I have put in a feature request to examine some of the special cases where we might not want this to happen (mostly involving retaining machine records). This change accounts for most of the diff (it had to be added to all FK references in the migrations too).
• Some methods have moved; reverse is one.
• User.is_authenticated is now an attribute.
• The settings MIDDLEWARE_CLASSES has been renamed to MIDDLEWARE.
• Updated custom middleware to inherit the helper/transitional mixin so that they conform to the new API.

[sheagcraig]

I'm noticing that no Munki items show up in the machine detail page right now. Looking into it...

[sheagcraig]

...solved.