Add Suite field to Release file

Apparently older versions of unattended-upgrades require the Suite field in the
Release file to function. This commit adds a Suite field which mirrors the
Codename, or $DIST.
Merge pull request #27 from haus/add_suite_to_release

Add Suite field to Release file
Fix freight-cache with no arguments.  Closes #26.
Quoting consistency.
Tab consistency.
(#28) Check for a TTY before stdin becomes a pipe.
v0.32
Fix #30.