Remove po directory from Ubuntu builds

git-svn-id: http://cantata.googlecode.com/svn/trunk@5213 b1e49159-3266-923f-9c3e-04f16369770a
Remove install instructions for Ubuntu build

git-svn-id: http://cantata.googlecode.com/svn/trunk@5214 b1e49159-3266-923f-9c3e-04f16369770a