Tilovell 908 987 curatedfeed perf and package uniqueness

Addresses #908 and #987. Curated Feeds are now run from the lucene Index, which has been modified to include a field stating which curated feed a package is included in. This greatly improves curated feed search performance. This PR also includes the change to make the CuratedPackages table properly uniquely indexable by pair (CuratedFeedKey, PackageRegistrationKey) so that we disallow adding dupes.