Fixed blank server list (issue #120)

- The blank server list that was shown when the user had no servers assigned to his account
has now been replaced with an error message.

NOTE: You will have to add the other translations yourself (only EN at the moment)
Updated translations and added alert class to error message
Merge pull request #138 from rtroost2012/hotfix/blanklist-fix

Fixed blank server list (issue #120)