Add i18n support and logging

[jamaljsr]

Closes #3 & #5

This PR is built on top of #2 so that should be reviewed and merged before reviewing this PR. Only the last two commits are new.

This update adds i18n support using i18next and react-i18next packages. Only an English lang file is included but more can be added easily in the future.

This PR also adds some basic logging infrastructure using the debug package. Here are some notes from the README on how to customize the logs that are outputted to the console.

Logging

Client-side logs are disabled by default in production builds and enabled by default in a development environment. In production, logging can be turned on by adding a couple keys to your browser's localStorage. Simply run these two JS statements in you browser's DevTools console:

localStorage.setItem('debug', '*');
localStorage.setItem('debug-level', 'debug');

The value for debug is a namespace filter which determines which portions of the app to display logs for. The namespaces currently used by the app are as follows:

• main: logs general application messages
• action: logs all actions that modify the internal application state
• grpc: logs all GRPC API requests and responses

Example filters: main,action will only log main and action messages. *,-actions will log everything except action messages.

The value for debug-level determines the verbosity of the logs. The value can be one of debug, info, warn, or error.

[guggero]

LGTM, great to have i18n and debugging capabilities added from start!