Remove display elements (except dateSet and subjectSet)
DIL-3868: Add display elements programatically

* Add equivalent-xml gem
* Add display elements to VRA image record
* Add a <vra:display> element to each *Set element in the VRA record,
  except for dateSet and subjectSet.
* Add pry-byebug gem for pry debugging funsies
* Add and populate display elements to VRA:image
* Ignore database.yml.pg
* Refactor adding display elements
Merge pull request #28 from nulib/dil-3867

DIL-3867 & DIL-3868 & 2 cool guys