ID of merged Described is always the lowest ID in the input Describeds

When merging `Described`s sets the `OutputContentMerger` will set the ID
of the chosen `Described` to the lowest ID present in its equivalence
set.
determine lowest id from chosen equivalentTo set
Move relatedLinks from Content to Described

Moves the `relatedLinks` field and related methods up the hierarchy to
__Described__ from __Content__ so a __Person__ has can also have
related links.
Add newEpisode field to Broadcast.
merge related links on equivalents
add ARTICLE link type
Add new method to query people by publisher
Publisher coyote.