Helpers for config and API client

[andrewn]

I'm trying to add Storybook stories for the FileNode component but this isn't possible because it imports Redux actions which rely on reading window.process.env, which throws an error in the storybook environment. 😢

I noticed that the code for reading the env var is duplicated throughout the app, so I've refactored into a helper called getClient(key). This also abstracts where the var is being read from, so in future we can read it from elsewhere, or try a few different places (local storage, then the env) without changing the calling code.

The biggest user of the env var is the API_URL in the redux actions. I've created apiClient which is an instance of axios that provides a single place to configure the API_URL and basic config that we want to apply to all communication to the editor API.

I have verified that this pull request:

• has no linting errors (npm run lint)
• is from a uniquely-named feature branch and has been rebased on top of the latest master. (If I was asked to make more changes, I have made sure to rebase onto master then too)
• is descriptively named and links to an issue number, i.e. Fixes #123

[catarak]

Thank you! This is awesome and cleans up the code a lot. One thing I'm noticing is that when I run the tests, I'm getting some warnings about the config variables being undefined:

I'm seeing these warnings in Nav.test.jsx, getConfig.test.js, FileNode.test.jsx, and Toolbar.test.jsx.

[andrewn]

I've changed getConfig so it doesn't warn when in the test environment.

I think this is good enough until we start writing tests that require these config values.

[catarak]

works for me!