[1.0] Scan for graphl queries in locations other than src.

[craigmulligan]

Carried over from discussion here: product-os/landr#25

[craigmulligan]

The problem:

Right now the relay compiler scans for grapqhl queries and fragments for all js files in "src" as well as any page component, unfortunately if a plugin is exposing it's own components or the user is putting components in another directory they are never compiled and added to graphql.

[craigmulligan]

I'd prefer to make the graphql compiler programatically accept paths via the bound actions api, in the same way you'd createPages() you could setgraphqlCompileComponent or something with a better name :)

[KyleAMathews]

I'd prefer to make the graphql compiler programatically accept paths via the bound actions api, in the same way you'd createPages() you could setgraphqlCompileComponent or something with a better name :)

This would be great too I think — the problem is it doesn't solve the use case of someone wanting to install a Gatsby-specific component that has an included GraphQL fragment. Unless we treat these components as plugins basically and make people add them to their gatsby-config.js

[KyleAMathews]

This PR added support for plugins including fragments #2320 (comment)