New argument for pulling specific post view stats

I wrote a conditional inside the wmp_get_popular() function to accept an argument that is a post ID. This allows the user to access the view count the plugin is keeping track of for a specific post. The returned object is the 4 view count statistics in the database table. 

I don't know if this fits in with the theme of the plugin per se, but I wanted to put all the good view count data to use.