Enforce contain naming conventions

[ashfurrow]

exlint-plugin-relay does this here: https://github.com/relayjs/eslint-plugin-relay/blob/master/src/rule-graphql-naming.js

The required message is:

Container fragment names must be `<ModuleName>_<propName>`. '

I think this might already be covered by the Relay compiler (or at least, with the Artsy Relay config). Still, a linter that gave in-editor underlining, errors, and auto-fixing would be worth it.