Phoenix 180

First revision for review.  There are some open points here.  Still no test case added to consume the stats.  Will do the performance test once the system is available with me.
See other examples here of how to get the PTable given the tenantId, schemaName, and tableName. You'd want to look it up and then use the PTable.getPhysicalName() to get the actual HBase table. See below for how to handle if there's a tenantId, but it would form a start/stop key that should be passed through the update stats method (it's fine to TODO this for now).