Fix bug in Utils.format that ignore falsy values.

Previously this would affect where clauses, e.g:
  User.findAll({ where: ['foo = ?', 0])
Would translate into:
  SELECT * FROM `Users`.`foo` = ?
Instead of:
  SELECT * FROM `Users`.`foo` = 0

lib/utils.js

@@ -47,10 +47,7 @@ var Utils = module.exports = {
     return connection.escape(s).replace(/\\"/g, '"')
   },
   format: function(arr) {
-    var query        = arr[0]
-      , replacements = Utils._.compact(arr.map(function(obj) { return obj != query ? obj : null}))
-
-    return connection.format.apply(connection, [query, replacements])
+    return connection.format.apply(connection, [arr.shift(), arr])
   },
   isHash: function(obj) {
     return Utils._.isObject(obj) && !Utils._.isArray(obj);