Fixes #6765 Moved the 'Settings' menu in the top menu

The settings menu is now visible on every page and doesn't require to click on the user name.

As I said on #6765, the first times I used Piwik I was very confused because I couldn't find this link.

![capture d ecran 2014-12-23 a 10 28 47](https://cloud.githubusercontent.com/assets/720328/5531259/85a4adc4-8a8e-11e4-9eae-f543541d68bc.png)