Check edit permissions in angular for appropriate pages

Also improve error page.  Fixes #2850
More json ingest framework

Including super inefficient schema validation, and copy of volume.json
from curation/spec.
Expose slot.excerpts in api

Excerpt modeling is still rather messy
Work on record movement on timeline
Loosen record removal source specifications

This allows removal (but not moving) of all records within a segment.
Include url in error messages