Turn houndstooth into a gem

[ShanaLMoore]

TODO: make this into a fork instead?

rake build

Concerns:

• support for hyrax and flexible metadata needs to change the schema a lot from the original houndstooth. so should we make a fork to support hyrax needs? Otherwise the validator will be invalid for hyrax's need to maintain backwards compatibility for others.
• What are the implications for aligning it to hyrax needs? Is it still m3 compliant?
• What is the m3 metadata standard?
• how would librarians feel about these changes?

TODO?

• flexible metadata profile
  • remove cardinality and index_documentation since our code doesn't use it.