fix blank lines that can appear in the Debian template

that was tested on a package with a replace and one without (naoqi_bridge and romeo_robot)
Can't this be more readable like so:

```
Build-Depends: debhelper (>= @(debhelper_version).0.0), @(', '.join(BuildDepends))		
@[if Conflicts]Conflicts: @(', '.join(Conflicts))@\n@[end if]@
@[if Replaces]Replaces: @(', '.join(Replaces))@\n@[end if]@
```

Haven't actually checked, but I believe the trailing `@` should cause em to swallow the newline.