Extract backports repo URI logic to a helper
Use default mirror with /debian-backports suffix for backports repo on Squeeze

Only fall back to backports.debian.org if the mirror URI does not end
with /debian.

Also make it possible to force the backports repo URI with
`node['debian']['backports_mirror']` attribute.
Merge pull request #7 from tmatilai/backports-mirror

On squeeze use default mirror with /debian-backports suffix for backports repository
Add backports-sloppy recipe

Configures squeeze-backports-sloppy suite on Squeeze:
  http://backports.debian.org/Instructions/#index4h2

On Wheezy issues an warning as wheezy-backports-sloppy will be created
only around Jessie freeze.

In all cases also includes the `debian::backports` recipe.
Merge pull request #8 from tmatilai/backports-sloppy

Add backports-sloppy recipe