[TYPO3-core] Login Screen

[Michael Stucki]

Hi folks,

I just noticed that we didn't change the login screen style for quite a long 
time. However, I always found it nice to identify different branch versions 
based on this welcome screen.

So what do you think? Shoud we keep the existing one, or create a new one? If 
anybody is interested to help, please send me a diff of the stylesheet.css as 
well as the new login image. And notice that nothing except the colors are 
allowed to be changed...

Thanks in advance!

- michael