log to syslog the byte range and content-type info when we know it
log to syslog the byte range and content-type info when we know it

Byte range info:
- `*/N` means all N bytes were sent
- `A-B/N` means bytes `A-B` (inclusive) of N were sent
- `-/-` means we sent a chunked-transfer and do not know the length (currently only in some error response cases, I think)

Content type info:
- `none` when we serve 204 No Content responses
- `unknown` when we don't know the content-type... should we change to application/octet-stream?
- a specific content-type we formulate from our service code
  - `application/json`
  - `text/plain`
  - `text/uri-list`
- or an arbitrary content-type for an object, which is under client control

informatics-isi-edu/hatrac,informatics-isi-edu/hatrac