daklib/upload.py: Use common base class for all exception.
HashedFile: Raise FileDoesNotExist if referring to a non-existing file

A custom exception is nicer to handle in the caller.
Import errno, used in Exception handling.

From a reject exception:

|   File "/srv/ftp-master.debian.org/dak/dak/daklib/upload.py", line 155, in check
|     if e.errno == errno.ENOENT:
| NameError: global name 'errno' is not defined
Merge remote-tracking branch 'paultag/paultag/bugfix/import-errno'
cron.unchecked: stop bothering with override files.
cron.unchecked: drop unused do_dists function.
dm-migrate: list source packages for which permissions were migrated.
Add first unit tests for GnuPG wrapper.
test_gpg.py: also check signature timestamp
test_gpg.py: test PGP messages and plaintext
dak make-pkg-file-mapping: ensure stable order

Include component and filename in the ORDER BY clause to ensure the
output order does not change.
dak make-pkg-file-mapping: do not include sources from other archives

Include only information about a source package's files if its .dsc is
in the requested archive.

Previously when xy_1.0-1 was in the requested archive and xy_1.0-2
using the same upstream tarball in a different archive, dak would
still include information about xy_1.0-2's upstream tarball resulting
in confusing entries on snapshot.d.o.

Reported-by: Salvatore Bonaccorso <carnil@debian.org>
daklib/checks.py: check timestamp of .changes signature

This allows to eventually drop old entries from the signature_history
table.
Merge branch 'debian-master'
Import the code written by abhishek

Import the code written by Abhishek Bhattacharjee during his Google
Summer of Code internship.
Properly parse command-line arguments

And also do some other cleanup
Do not override dak's own logs and print better console output

In future, the dak logger must be used.