Add missing (official) plugins & little fixes (#3718)
Add missing (official) plugins & little fixes (#3718)

* Add missing (official) plugins & little fixes

As talked about in:
https://github.com/gatsbyjs/gatsby/issues/3708

Fingers crossed that I didn't mess up the alphabetical order :P
(I actually changed the order a little bit)

* Add gatsby-source-graphcms

mingaldrichgan/gatsby,ChristopherBiscardi/gatsby,fk/gatsby,ChristopherBiscardi/gatsby,mingaldrichgan/gatsby,fk/gatsby,ChristopherBiscardi/gatsby,gatsbyjs/gatsby,0x80/gatsby,fk/gatsby,gatsbyjs/gatsby,gatsbyjs/gatsby,mingaldrichgan/gatsby,gatsbyjs/gatsby,ChristopherBiscardi/gatsby,0x80/gatsby,gatsbyjs/gatsby,gatsbyjs/gatsby,0x80/gatsby