Merge apt--mvo--0

Merge apt--mvo--0
Patches applied:

 * michael.vogt@canonical.com--2004/apt--mvo--0--patch-5
   * added apt-key update method

 * michael.vogt@canonical.com--2004/apt--mvo--0--patch-6
   * if a sign-file download fails, delete the the partial download in "partial/" also

 * michael.vogt@canonical.com--2004/apt--mvo--0--patch-7
   * changelog updated, version is now 0.6.27ubuntu4; added DEB_BUILD_PROG_OPTS to debian/rules

 * michael.vogt@canonical.com--2004/apt--mvo--0--patch-8
   * removed Release.gpg files in partial/ before fetching a new one

 * michael.vogt@canonical.com--2004/apt--mvo--0--patch-9
   * some comments about the pkgAcqMetaSig::Custom600Headers() added

 * michael.vogt@canonical.com--2004/apt--mvo--0--patch-10
   * fix permissions in po/

 * michael.vogt@canonical.com--2004/apt--mvo--0--patch-11
   * use gpg --with-colons