[PATCHSET] pungi: allow 'full' and 'selfhosting' tree builds

[Bill Nottingham]

The attached patchset adds the following functionality to pungi:
- building 'full' trees, that include all subpackages for any included
  package
- building 'selfhosting' trees, that solve the package set for, and include,
  any build dependencies

This is a rebase of some patches sent earlier this year.

 bin/pungi.py        |   23 ++++++++++
 pypungi/__init__.py |  109 ++++++++++++++++++++++++++++++++++++++++++----------
 2 files changed, 112 insertions(+), 20 deletions(-)

Bill