Add request to Bridge Troll API

[LauraKirby]

• Remove reference to locally stored data and use Bridge Troll API
• Update Readme to include instructions for getting set up locally
• Remove console.log of events count since it is not currently included within JSON response. It looks like adding it within Bridge Troll will not be too difficult. I have already figured it out, if it is something we should move forward with.
• To do: identify any additional items we would like to have from the JSON response and discuss how that would be represented on the map.

[ultrasaurus]

thanks for this PR! I don't think it'll work yet because some locations don't yet have geo data in Bridge Troll (maybe the "external" events?)

For example:

  {
    "url": "http:\/\/www.meetup.com\/Mad-Railers\/events\/119755612\/",
    "title": "Ruby on Rails Outreach Workshop for Women",
    "location": {
      "name": "Madison Ruby & MadRailers",
      "city": "Madison, WI USA"
    },
    "organizers": "Jim Remsik & Desi McAdam",
    "sessions": [
      {
        "starts_at": "2013-08-21"
      }
    ],
    "organization": "RailsBridge",
    "workshop": true
  },

[ultrasaurus]

waiting on: railsbridge/bridge_troll#499