Store similar content

A new object on complex Content stores similar content. This
is output in the simpole model on Description, controlled by
the SIMILAR annotation.

A new publisher, METABROADCAST_SIMILAR_CONTENT,  has been added
for the MetaBroadcast similar content computations.
Merge similar content according to precedence on output
Merge pull request #183 from atlasapi/mbst-7489-store-similar-content

Similar content