debian/rules: switching to debhelper

Adding the needed changes that comming by the switch to debhelper
as build system. Finally are more changes to the rules file needed.
debian/mozconfig*: adding mozconfig files

Adding various mozconfig files for building ID and it's corrosponding
debug binarys.
There is 'mozconfig.default' that includes the basic instructions for
all builds. This file is included later by any other mozconfig files to
use the variables there.