Add specs for gists comments api.
Add specs for gists comments api.

anabhilash619/github,samphilipd/github,MalachiTatum/github,yaoxiaoyong/github,piotrmurach/github,durai145/github,cocktail-io/github,GistBox/github,peter-murach/github,wicky-info/github,firstval/github,befairyliu/github,joshsoftware/github,davengeo/github