Bump version of Haystack

Haystack 2.2 contains a lot of bugfixes, including a fix for Python 3.
It seems like we'd do everyone a favour by upgrading.
Workaround for pysolr not supporting Solr 4 error messages

Generally, Haystack now seems to clean the facet queries. But there's a
UnicodeBug lingering that is triggered because pysolr 3.1 doesn't
support Solr 4's JSON error messages. Support for that has just been
added on the master branch, but the potential for the UnicodeDecodeError
is still there until my PR #127 is merged.

Closes #1060.
Fix wrong padding for adding reviews

I unintentionally added different padding to a few different classes in
9fae504. As the facet area actually looks better with the standard
padding of side_categories, I just removed the line.

Fixes #1464.