Add missing configuration instructions for dashboard chart ElasticSearch code

[brylie]

We are missing details about how to configure our project to access the ElasticSearch engine for dashboard analytics. @frenchbread, please update the team as to how we can configure our development environments to support remote ElasticSearch queries.

[frenchbread]

Here is a pull request that has been already merged to develop. It basically contains all needed fixes. The structure of settings.json file is provided here.

[frenchbread]

Summing up all latest changes and configs:
For having everything up to date and working,

1. Pull the lastest commit from develop branch.
2. Create settings.json file (if it does not already exist)

Here is its contents (host address is the usual one):

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

When running meteor app, do it like this:
meteor --settings /absolute/path/to/settings.json