Wrong Schema.prototype.sufficientRemoveConditions function

If 'key' is 0, for example
uid: cql.int()
and we try to remove uid = 0
like User.remove({uid: 0});
we get a false error in the function
```
Schema.prototype.sufficientRemoveConditions = function (conditions) {
var keys = this.lookups
? Object.keys(this.lookupTables).concat(this.primaryKeys())
: this.primaryKeys();

return keys.every(function (key) {
return !!conditions[key];
});
};
```
"Must pass in all primary keys when using lookup tables"