CYB-332 CSV taking nearly 4.5 minutes to generate

  * altered to get all data directly via SQL
  * no use of the Decorator anymore -- pure SQL + Ruby

Adding, removing or retitling fields is easy with this code; as is changing the conditions (currently, only actions taken by a student show, although getting comments and likes/dislikes still count to the student's score).

[CYB-332 CSV taking nearly 4.5 minutes to generate](https://jira.ets.berkeley.edu/jira/browse/CYB-332)