Only two cases of the Sort enum being converted to a string. Added a call to both uses to convert the enum name to lower case.
Only two cases of the Sort enum being converted to a string. Added a call to both uses to convert the enum name to lower case.

This brings it into compliance with the documentation at https://www.reddit.com/dev/api#GET_user_{username}_submitted.

angelotodaro/RedditSharp,pimanac/RedditSharp,theonlylawislove/RedditSharp,RobThree/RedditSharp,epvanhouten/RedditSharp,chuggafan/RedditSharp-1,justcool393/RedditSharp-1,SirCmpwn/RedditSharp,IAmAnubhavSaini/RedditSharp,tomnolan95/RedditSharp,nyanpasudo/RedditSharp,Jinivus/RedditSharp,CrustyJew/RedditSharp