Add linting and other development supports

[colinbdclark]

It should be possible to lint the code and related artefacts (e.g. JSON) to ensure syntactic correctness. This can be done using Fluid/GPII's infrastructure.

[colinbdclark]

@the-t-in-rtf suggested that I should use gpii-grunt-lint-all—"lint all the things with one dependency, two if you want eslint linting in your IDE."