Set strict-all-tables for mysqld.

Summary:
epriestley told us to!  At
   http://phabricator.khanacademy.org/config/issue/mysql.mode/

  | By default, MySQL will fail silently and continue when certain error conditions occur. Sometimes contuining does the wrong thing. For example, inserting too much data into a column will cause silent truncation (and thus data loss) instead of failing in an obvious way that we can fix. These behaviors can also create security risks. Enabling strict mode raises an explicit error instead and prevents this entire class of problem from doing any damage.

Test Plan: Fingers crossed.

Reviewers: alpert, benkomalo

Reviewed By: alpert, benkomalo

Differential Revision: http://phabricator.khanacademy.org/D8469