Show mapping-sensitive info on the hits page

* Hide errors that now have a mapping
* Indicate in muted-text what a hit was and what the mapping says now
* Text of "Check mapping" changes to Add Mapping / Edit Mapping as appropriate
HitsMappingRelations.refresh! should cope with c14n'd query string
Mappings update their hits on save

* Also unlink old hits when path changes
Import of either new hits or mappings should refresh relations
Refresh operations to $stderr, not logger.info

* Otherwise it doesn't look like anything is happening for minutes
Do linked hits updates in batch

* There may be many, and #find will be slow
Rename the rake task to match its class