[5.5] Allow to automatically use where/whereIn or whereNot/whereNotIn methods in DatabaseRule

[mnabialek]

This adds additional improvement to where/whereIn and whereNot/whereNotIn methods in DatabaseRule trait. If you don't know what exactly is value (array or string) probably we don't want to force user to write code like this:

if (is_array($value)) {
   $rule->whereIn('column', $value);
}
else {
   $rule->where('column', $value);
}

If merged, in such case either where or whereIn can be used with exact same result. It will be especially useful if request data is used as value.