Updated musicbrainz-unittest.sql test data for new schema.
Added new Area entity, and removed deprecated Country entity.
Updated Artist entity and ended new area, begin_area, end_area columns.
Removed deprecated country and releaseDate from Release and 
added releaseUnknownCountry and releaseCountries.
Updated values of ReleaseGroupPrimaryType.
Removed deprecated TrackList and restored mapping from Medium to Track.
Updated Track and implemented getNumber, getGids, getLength,
getLastUpdated.
Made ReleaseUnknownCountry lazily loaded in Release.
Updated values of AreaType.
Added or updated unit tests for ArtistType, Gender, and
ReleaseGroupPrimaryType.
Cleaned up Partial Date.
Added tests for lazily-loaded properties in Artist.
Added comment for length property to Track, added test for lazily-loaded
property in ArtistCredit.
Upgraded dependencies (Spring to 3.2.2.RELEASE, Guava to 14.0.1, slf4j
to 1.7.5, joda-time to 2.2).
Added methods getById, getByGid, and getByArtistAndName to TrackDao.
Updated changelog and version in README.md.
Updated/added license headers.
Updated version in README.md.
Merge branch '2013-05-15_schema_change_release'
Updated changelog.