Onward sequencing

This PR introduces a new module ```sequence.js``` which acts as a getter and setter for us to store and retrieve contextual article sequences in localStorage, based on users previous journey and intents.

(P.s. If you are asking "didn't swipe nav do this", you are indeed correct, this is a leaner version, my next PR will be deleting the swipe code)

#### Example
```JavaScript
define([
    'modules/sequence'
], function(
    'sequence'
)){

    var seq = sequence.getSequence();

    //seq -> ["/p/3k4vt", "/p/3k44f", "/p/3k44b"]

});
```

![Repetition](http://25.media.tumblr.com/e9ae792a3534dcdcdb7d011431843b46/tumblr_mioibvV7jL1qgdc0oo1_500.gif)