Fix a rare cause of sync conflicts

Sometime in the past SQL datetimes saved to the server could be
interpreted as multipart dates, causing the date portion to be stripped
from the visible field. I fixed this previously on the server, but a
full sync could result in conflicts for any such values that synced
down. Instead, overwrite the local version (keeping Date Modified the
same) if there are no other changes.
Show redirect URL in the sync stream listener (for file downloads)

Also consolidate the display-URL-password-hiding logic in http.js