Make flash messages fixed and sticked to bottom

According to #4653 i've remade flash messages in a more user friendly way. They are different than in a screenshot attached to the issue cause they looked ugly that way. Idecided to make them exactly as they were but for now, they are semi transparent (80%) and sticked to bottom of the screen. 

I've also reduced fadeOut timeout to 3000 ms cause they don't need to last so long.

Here is how it looks right now:
![zrzut ekranu 2013-08-17 o 12 43 27](https://f.cloud.github.com/assets/581569/980890/ead285ca-0729-11e3-8eb9-cc6e64820b5d.png)