Merge remote branch 'ansgar/signatures-2' into merge

Merge remote branch 'ansgar/signatures-2' into merge

* ansgar/signatures-2:
  tests/test_parse_changes.py: add another testcase
  daklib/gpg.py: capture stderr
  tests/test_parse_changes.py: do not require signatures
  daklib/utils.py (parse_deb822): include PGP armor in filecontents
  tests/test_parse_changes.py: update for new SignedFile exceptions
  daklib/utils.py (parse_deb822): use SignedFile to handle PGP signature
  tests: dsc/4.dsc is invalid
  examine-package: use SignedFile to remove PGP armor
  daklib/gpg.py: small library for PGP-signed files

Signed-off-by: Joerg Jaspert <joerg@debian.org>