Move files from app/models to lib

- Move classes and modules that are not model-like (that don't do
  persistence) into lib.
- Update autoloading in the engine's bootstrapping as a result of this
- Clean up some autoload statements in krikri.rb as a result of the
  autoloading changes.
Merge pull request #43 from dpla/rearrange-modules

Move files from app/models to lib
Add JSON record factory
[wip] JSON parser; specs failing because of something w/ Marmotta
JSONParser implementation; needs some sanity checking.
Add some complexity to JSON OriginalRecord factory
Revise JSONParser with type checking; improve parser specs
Readd JSONPath support and specs to test
Rubocop cleanup