Introduce Draper, Reorganize FacetValue Presenters

[mbarnett]

Context

As part of the introduction of presenters for the Metadata renderers for OAI, we've decided to bring in the Draper gem for presenters/decorators. Metadata renderers are being finalized in a separate branch/PR.

Changes

• Adds a dependency on Draper.
• Moves existing facet presenters into a top-level decorators directory for consistency with Draper decorators, and changes the terminology accordingly. Facet decorators continue to use a non-Draper base class, as each decorator translates an individual value of FacetValue, whereas Draper is based on wrapping a class. We could explore changing the way FacetValues are wrapped entirely, but the two approaches co-exist transparently from the view layer's perspective via a consistent helper interface.
• Changes the present and presenter_for helpers which wrap models in presenters for the view to use Draper decorators where applicable.

[ualbertalib-bot]

	1 Warning
⚠️	There are code changes, but no corresponding tests. Please include tests if this PR introduces any modifications in behavior.

Generated by 🚫 Danger

[murny]

Nice work 👍