Revert "Delete unused profile parsing code."

This reverts commit cf9088b80d038fa7ef0daf8b6f9af8e6b96b65d1.
Switch back to parsing HTML for user profiles.
Fix/get more from user profile parsing.

- Parse the user ID.
- Extract just the numeric post rate, without the "per day".
- nil-out missing profile pictures (so they disappear from cache when deleted
  by the person).