Merge pull request #182 from atlasapi/fix-series-ref-comparison

make SeriesRef.compareTo more consistent
Add debug method to get indexed document
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 branch 'mbst-7489-store-similar-content' into stage