Feature/chart code refactoring

[frenchbread]

Here is settings.json file example (elasticsearch.host parameter is required for app to fetch analytics data):

{
  "api_umbrella": {
    "api_key": "...",
    "auth_token": "...",
    "base_url": "https://.../api-umbrella/"
  },
  "elasticsearch": {
    "host": "http://...:14002"
  }
}

[brylie]

es might be improved by adding more semantic details. E.g. ApiUmbrellaElastic.

[brylie]

Add comments to describe this line.

[brylie]

Use JsDoc style @params here, as well as the general JsDoc comment style.

[brylie]

Month length should not be hard-coded. Here are a couple of possible methods for getting the number of days in any given month:

• http://stackoverflow.com/a/1810990/1191545
• moment(year-month-day).endOf('month');

I believe our project already contains Moment.js, which has an elegant API for JS dates.