Previous version broke storybook build.

Issues are logged last in the console. To make them easier to read.

If any issues remain, an alert() is done to warn developers when
headlamp is compiled in development mode. This alert() can be
disabled with the REACT_APP_SKIP_A11Y=true environment variable,
which is necessary when beginning development on new components.

Hopefully these two measures will help prevent more issues escaping
review, since the console log was quite noisy and can be forgotten.

Started a section in the documentation on a11y tools.

Fix integration with redux devtools

One main benefit of redux are the great tools.
See [redux-tools](https://github.com/reduxjs/redux-devtools)

Rename backend server to headlamp-server

Plugin improvements

So the assets are all inside the dist/main.js

I think before because two loaders were being used images were not
displaying properly.

Using style-loader and css-loader headlamp plugins. The styles are
packed into the output main.js file, not as separate css files.

It's only meant to check the typescript for issues not generate files.

github: Fix golang version to one version

The former name was too generic, which made it difficult to spot, and
could clash on Windows as well.

This patch renames it as headlamp-server but keeps as /headlamp/server
symlink in the container image, for backward compatibility.

plugins: Show how to use styles inside a plugin

Fix plugin imports again

The include path was relative to headlamp-plugin in node_modules, so
it didn't work when just extending the plugins-tsconfig.json file.
This change set the path to be the plugin's own top directory + src
files, so it allows plugins' tsconfig to simply extend the mentioned
shipped tsconfig instead of having to override the "includes".

We want to allow an import like:
import { makeCustomResourceClass } from '@kinvolk/headlamp-plugin/lib/K8s/crd';

but the plugins-tsconfig.json was not resolving these paths correctly
due to a mix of legacy/invalid type path and also the baseURL being set
to "." which made the paths be resolved in the headlamp-plugin module
in module_nodules and not from the plugin's top dir.

Headless app fix

Fix default class names

Docs had been created without a plugin that renames the default
exports, so a lot of classes were names as default.

This patch uses the "typedoc-plugin-rename-defaults" package which
renames the default exports, otherwise e.g. classes that are part of
the lib/k8s modules would be exported as simply "default".

Plugin changes

Bundled app plugins