CYB-59 Add a CSV export for points

  * header line is the DB field names; easy to change (use a Ruby Hash to map field names to English, or use 18n)
  * all fields but 'id' are included (very easy to remove, edit the list used by #pluck)

[CYB-59 Add a CSV export for points](https://jira.ets.berkeley.edu/jira/browse/CYB-59)