Add EquivalenceSummary and (de)serialization configuration

EquivalenceSummary records computed candidates and resultant
equivalents of the equivalence process. This intended for use in other
equivalence settings, i.e. the results of a Brand's children can
influence the result of the Brand itself, or vice-versa.

Any other use, such as resolving content, is probably not a good idea.
Remove summariesForChildren method
New class Synopses, wrapping multiple descriptions, and /simple/Descriptions, which is the simple model equivalent
Remove Synopses/Descriptions object, move short/medium/long descriptions to the top level
Add Channel to simple model
Add CHANNEL_SUMMARY annotation
Merge pull request #84 from atlasapi/mbst-3871-channel-summary-annotation

Add channel_summary annotation
Choose PA images in preference to other broadcasters
Merge pull request #83 from atlasapi/mbst-3606-pa-multiple-descriptions

Mbst 3606 pa multiple descriptions
Merge pull request #76 from atlasapi/mbst-2993-stream-equiv

MBST-2993 stream equiv
Merge pull request #85 from atlasapi/mbst-3924-pa-image-preference

Choose PA images in preference to other broadcasters
Upgrade jackson version
Use the same ordering for image precedence as for publishers in general
Merge pull request #86 from atlasapi/mbst-3924-pa-image-preference

Use the same ordering for image precedence as for publishers in general
fix equality in RelatedLink
Merge branch 'master' into mbst-3880-youview-ingest
Add Aliases to simple model Broadcasts