Launched in September, Facebook debuted a test allowing it to place ads on third party mobile apps. Well, the social media site has decided to put the kibosh on these efforts and will halt the service by the end of December. In an email to AllThingsD, Brandon McCormick stated, “While the results we have seen and the feedback from partners has been positive, our focus is on scaling ads in mobile news feed before ads off of Facebook.  [Source: AllThingsD]