Remove duplicate messaging for error validation when leaving a review

[danielngira]

In PR #261, we added the ability to leave a review and rating on a game in the game detail page that was implemented in issue #40. One of the conditions for leaving a review is that either the review or the rating must be field. That is they can't both be left blank. By the end of issue #261 the form validated this correctly. However, if you try to leave both of the fields blank, it will give off two error messages. In this issue, you will fix this issue that arises from the ReviewForm so that it only gives off one error message. Here is a visual of what you are meant to fix.