Better integration in Redmine, by using the same behaviour as Redmine itself uses

Hi,

I changed these 3 things:
1. Added german translation
2. Changed the way you display the block title. Redmine links the title to the issue page. Your plugin will now do the same. This gives the user a continous user experience.
3. Your plugin add queries to the available blocks, even if it is already used. This is now fixed.

Best regard,
Daniel