Added extra field to metadata and add it to index
Add option to select index-fields.xsl for metadata depending on root type.

This allows a responsible party or extent to be indexed differently from each other or from a MD_Metadata.
fixed bug with metadata extra field
Move index-fields to a folder allowing for specific indexers for specific roots.
Changed how version numbers are compared in database migration and ensured tests pass
Merge branch 'develop' of github.com:jesseeichar/core-geonetwork into develop
Pass connection to Database migration tasks instead of a single statement.
Provide a more robust migration of harvester settings to harvester settings table.