Bug fix - always prefer exact package matches, for all repositories.

Previously, roar-ng II preferred exact matches (e.g packages whose first name
matches) over non-exact ones (e.g packages with a matching alternate name).
However, non-exact matches were dropped during the search of a specific package
database.

This commit changes this behavior, so package databases are searched twice: once
with alternate names support disabled, then with this support enabled. This
prevents false positives when a cached package entry has an alternate name that
matches another, non-cached package name.

A missing packages which was not downloaded and processed due to this bug was
added to the package list. This bug was discovered when roar-ng II refused to
download the Debian Wheezy "locales" package when "locales-all" is cached. The
alternate name of the latter caused roar-ng II to pick its entry instead of
finding an exact match.