Really enable the STRICT_TRANS_TABLES, let's see if any of our tests fail

Refs https://github.com/piwik/piwik/pull/279

.travis.yml

@@ -92,6 +92,8 @@ before_script:
   - "sudo /etc/init.d/mysql.server start"
   - mysql --version
   - mysql -e "SELECT VERSION();"
+  # Enable sql_mode STRICT_TRANS_TABLES as it is the new default in Mysql 5.6
+  - mysql -e "SET GLOBAL sql_mode = 'NO_ENGINE_SUBSTITUTION,STRICT_TRANS_TABLES'"
   - mysql -e "SELECT @@sql_mode;"
   # Setup Piwik stack
   - ./tests/travis/initiate_ui_tests.sh