Feature/mie 1337 require.js build changes to remove hardcoded id #17

This PR corresponds to a previous one: https://github.com/natgeo/modules-activitystream/pull/17
The difference is, this one points to develop instead of followprototype (which is already merged).

Separates the require.js's configuration (now lives in config.coffee) from the initialization (main.coffee) of the module in order to remove the user's hardcoded id from the build file. We also added 'ActivityStream' as a separated module.

The example instanciation of this module was moved to app/index.html

Changes in method for getting new activities due some changes on the Service's API
Can we do this with the `em` unit?