Enabling runtime stats for hbase operators

This is the first set of changes to collect the runtime stats info for
hbase tables and operators. It contains:
1) Populate the estimated row count in hbase access TDB.
2) Collect the hbase access time and accessed row count at the JNI layer
(only for select operations now).

Partially reviewed by Mike H. and Selva G.

Removed the part that devides the estimated rows by number of ESPs based on the comments

Change-Id: I5a98a8ae9c4462aa53ad889edfe4cd8563502477
Merge "Enabling runtime stats for hbase operators"