Feature/qr generation

Created the QR-Generation for the frontend.
Sorry in front for the last commits -> went full retard with sourcetree and so on ... main.less made troubles => i added the playlist styles to it as well as my styles

I basically created, that the QR-Code can be seen in the event page, as well as the shortend link.
Problem that we have: creating the shortend link is really slow (bitly takes some time here ...), but svg creation is quite fast.

Therefor => Creation of the short-link cannot be in the event creation (also ... the front end controls how the link looks like ... so we just can create it AFTER the event was created).
To make it useable, i introduced a new collection that just stores long/short pairs - so we have the connection to bitly only once. QR Code is still generated every-time but is extremly fast.

Also limited the QR Code to 200px, otherwise IT IS HUGE O_O.
![current](https://cloud.githubusercontent.com/assets/1864641/5555249/e6be6934-8ca4-11e4-9a41-17dde951062e.png)