NING-13328: Huge refactor of the metrics/counter system.  This does away with the concept of identifier categories and counter subscriptions; the database schema is also changed so that there is a row for each counter in each namespace.  The distribution of each counter is now stored in a format that does not need to be loaded completely into memory before use.  This will make top N queries and make uniqueId filter queries use less memory.
NING-13328: Small fixes to bugs discovered in testing.  Deserialization of uniqueCount was depending on size of distribution, but this doesn't work if distribution is excluded.  Also the dates were being serialized as epoch time rather than iso dates
Updating release plugin based on sonatype documentation
[maven-release-plugin] prepare release metrics.collector-2.0.9