Show Feedback guide on demand

Fixes #2060. There is an icon that toggles the popover on click. In addition there is an info alert that can be hidden by using a cookie (introduced jQuery cookie). Using the same icon in both cases help to understand the idea of the icon.

![bildschirmfoto 2014-11-24 um 18 25 10](https://cloud.githubusercontent.com/assets/5362483/5169649/a58d86f6-7409-11e4-88ad-26586cf6adf0.PNG)

![bildschirmfoto 2014-11-24 um 18 29 44](https://cloud.githubusercontent.com/assets/5362483/5169652/ab642eb8-7409-11e4-9eb3-3df1f686448f.PNG)