Removing WithLinkedResource module

As per our ongoing discussion of projecthydra-labs/hydra-works#4

Given that we are soliciting use cases, this may not make the cut.
So instead of cluttering the code, lets kill it and bring it back if
needed.

Attention: @mcritchlow as you are reviewing the existing structure.

Closes #4
Merge pull request #16 from projecthydra-labs/remove-linked-resource

Removing WithLinkedResource module
Adds UCinn LinkedResource use case.
Adds Northwesten Playlist Use Case
Adds Northwestern DisplaySet and AdminSet use case.
Merge pull request #26 from projecthydra-labs/feature/nu_use_case

Adds Northwestern's Set Use Cases
Merge pull request #24 from projecthydra-labs/feature/uc_use_case

Adds UCinn LinkedResource use case.