Per-(table, columnFamily) metrics with configurable table name inclusion

As we kept adding more granular block read and block cache usage statistics, a combinatorial explosion of various cases to monitor started to happen, especially when we wanted both per-table/column family/block type statistics and aggregate statistics on various subsets of these dimensions. Here, we un-clutters HFile readers, LruBlockCache, StoreFile, etc. by creating a centralized class that knows how to update all kinds of per-table/CF/block type counters.

Table name and column family configuration have been pushed to a base class, SchemaConfigured. This is convenient as many of existing classes that have these properties (HFile readers/writers, HFile blocks, etc.) did not have a base class. Whether to collect per-(table, columnFamily) or per-columnFamily only metrics can be configured with the hbase.metrics.showTableName configuration key. We don't expect this configuration to change at runtime, so we cache the setting statically and log a warning when an attempt is made to flip it once already set. This way we don't have to pass configuration to a lot more places, e.g. everywhere an HFile reader is instantiated.

Thanks to Liyin for his initial version of per-table metrics patch and a lot of valuable feedback.