Follow Prototype: Users being followed and their activities

    Adds the ability to display members that the current user is following and their activites.
    Activity's icons are now displayed using css instead of an tag.

This pr was based on https://github.com/natgeo/modules-activitystream/pull/12/
Not specific to your PR, but we need to refactor this repo so that we do not have test objects in the code that runs in the browser. All the test code should be in the tests directory.