Center the auto update dialog to the main UMS window
Removed inconsistent sychronization which locks stop scanning
Formatting
Removed not necessary null checks
Fixed Some bugs
Solve the bug reported in
https://github.com/UniversalMediaServer/UniversalMediaServer/issues/270
Removed double null check
Fixed renderer selection
Revert "Fixed renderer selection"

This reverts commit eae64f56de83e4a844483856a0105652087d4bc5.
Fixed renderer selection