Test quoting integers when comparing a string column with integers.

An equality with a string column and integer like

  SELECT * FROM `users` WHERE `login_token` = 0 LIMIT 1;

will match match any string that doesn't start with a digit in certain
databases, like mysql. Make sure we quote the integer to avoid this
problem in a database independant way.
Merge pull request #162 from dylanahsmith/quote-integers

Test quoting integers when comparing a string column with integers.