Added simple link to top-bar on pencilboxes

We will keep track on people coming in from other pencilboxes by
referrer. We can add tracking with an event later when we do some A/B
testing.
Fixiing cta branding bar on smaller resolutions

Feel free to improve further!
Merge pull request #7 from michiels/mixpanel_branding_track

Added simple link to top-bar on pencilboxes.