Explicitly add ruby-filemagic as a dependency since we'll be using it directly to do some Master Creator stuff.
Breaks out the nontrivial amount of code required to get file type working into its own module.  Deletes the two XML content file types and adds Zip/Text File in their place.
Adds three new fixture objects that we will use for testing purposes down the line.
Updates the names we expect image derivative objects to have.
Update content_objects to look for the right model names.
Makes the helper methods in this module private.
Pushes master object creation into a job.  Updates the controller to make this work.
Removes the master creator module.

The current job based implementation does not abstract back out into code that would be usable very well, so for the moment the ContentCreationJob is going to be responsible for that work in toto.  Will at some point come back to it and clean things up.
Implements a working content creation job and some basic tests for it.
General cleanup.
Merge branch 'develop' of https://github.com/nu-lts/drs into feature/nu_file_redo
Merge branch 'develop' into feature/nu_file_redo

Conflicts:
	Gemfile.lock

Keep this branch fresh.
Adds audio and video file types to our list of possible content types.
Loops audio/video file creation into the upload process.  We now handle anything that subtypes to audio/video correctly.
Updates transformations.rb to be aware of MsexcelFile derivatives, even if it doesn't do anything with them currently.  More work on that is pending barring some changes to hydra derivatives.
Eliminate unneeded permission assignment callback in deposited_by_bill trait.
DRY
Dry up repeated code in the transformations spec with a context setting helper method.
Merge branch 'feature/nu_file_redo' into feature/test_cleanup

Merging in nu_file_redo so I can write tests over it.
Adds more fixture file types to do testing with.