Support modular .graphql files

[schrockn]

Right now grapple only supports a single graphql file. This will become quite unwieldly as systems grow. There should be the capability of modularizing graphql files you can have many graphql files and many corresponding groups of generated kvetch, pent, and graphql files.

foo/foo.graphql foo/pent/ foo/kvetch/ foo/graphql_schema/

and so forth.