clicks.js: Plugin for clicktracking

 Using this plugin you can track every click a user makes on a page.
 Configuring it is works as follows:

 ```javascript
	BOOMR.init({
        beacon_url: "<beacon-url>",
        clicks: {
          click_url : "http://<seperate-clicktracking-beacon-url>",
          onbeforeunload : false
        }});
 ```

 Using a seperate url allows to have a seperate server responsible for
 handling a bigger load than your beacon server given that a typical
 user will be clicking more than once on an average page.

 You can use this plugin in one of two ways:

  - `onbeforeunload : false` => Sends click-tracking beacons immediately
    upon click_events happening
  - `onbeforeunload : true` => All Clicks that have been tracked are
    sent at once upon closing the page

 Data sent to the beacon-server will contain the following:

 - `element`: the name of the element that has been clicked
   (li,a,button,span etc)
 - `id`: possibly set ids on the element
 - `class`: a list of all classes assigned to the element
 - `document height/width`: the size of the document
 - `viewport height/width`: the size of the browser window

 Information like this allows you (for example) to drill deeper into
 what impact a change in the UI had(AB-Testing) or see which size most
 users view your page which can allow for better optimized media-queries
 for the formats used by the user base and heatmaps for the page as it
 exists.
Merge pull request #13 from andreas-marschke/clicks

clicks.js: Plugin for clicktracking