Issue/252

@julen can you review this PR?
I'll add Monthly activity chart in a next commit to close issue #252.
No need to create the query string manually. You can use [jQuery.param](http://api.jquery.com/jquery.param/) and pass a dictionary. It'll automatically create a proper query string and encode the URI components too. So:
```
newHash = $.param({
  'user_id', PTL.reports.userId,
  'start': PTL.reports.dateRange[0].format('YYYY-MM-DD'),
  'end': PTL.reports.dateRange[1].format('YYYY-MM-DD'),
});
```