move changelog back to UNRELEASED as 0.6 was not actually uploaded
Add missing fonts-font-awesome build/binary dependencies

Use a versioned dependency as the fonts directory had a different name in
earlier releases.
Avoid some error messages noise when calling generate-index without any existing test data

In particular, these:

expr: syntax error
I: Updating global status...
grep: data/unstable-amd64/packages/*/*/latest.json: No such file or directory
grep: data/unstable-amd64/packages/*/*/latest.json: No such file or directory
grep: data/unstable-amd64/packages/*/*/latest.json: No such file or directory
Drop debci-test --reason option

Make debci-batch put the reason into the status directory directly. This avoids
unnecessarily passing around the reason.txt file to and from debci-test, which
would not work for remote workers.
Fold debci-cleanup into debci-generate-index

It's better suited there as debci-batch will soon request package tests
asynchronously.