Remove dependencies from nm.debian.org metapackage

debian.org-nm.debian.org depends on python-flaskext.wtf & python-wtforms which
are not part of squeeze and (at least for the former) difficult to backport;
this makes the package uninstallable and hence currently not installed on
nm.d.o, which makes the whole effort of keeping the metapackage, pointless.

Remove the dependencies (temporarily?) that are locally installed anyway, as to
install the package again.

Suggested by Enrico Zinni, RT #3345

Signed-off-by: Faidon Liambotis <paravoid@debian.org>