use symbols for relationship names
add has_model assertions for the whole ActiveFedora::Base hierarchy
add additional indexing to some OM terms
update to active-fedora 6.x and solrizer 3.x
remove active-fedora <5.x version checking logic.
remove ActiveFedora::Relationships
remove Solrizer::FieldNameMapper reference
remove utc date mapper
mark ng_xml as changed instead of content.
use solrizer to calculate field names
use the new solrizer 3.x insert field API
use solrizer to calculate field names
mark Editable#agreement= as pending
use the objectType :facetable field instead of the :string field.
bump to dor-services 5.x