Added Gist(github) adapter
Added Gist(github) adapter

zyuhel/Embed,RJacksonm1/Embed,okatsuralau/Embed,oscarotero/Embed,JanPetterMG/Embed,thenextweb/Embed,davereid/Embed,daveross/Embed,Soullivaneuh/Embed,mburtscher/Embed,philrennie/Embed,younes0/Embed