Remove backticks from SQL statements

Summary: Remove backticks from SQL statements for consistency. In most places, we don't use backticks around table/field names, so at least be consistent about this.

Test Plan: Learned what backticks are used for in MySQL.

Reviewers: eadler, epriestley, #blessed_reviewers

Reviewed By: eadler, epriestley, #blessed_reviewers

Subscribers: epriestley

Differential Revision: https://secure.phabricator.com/D13267