Enabling runtime stats for hbase tables and operators

This is the third set of changes to collect the runtime stats info. Part
is to address the comments and suggestions from last review.
1) Instead of passing the hbase access stats entry to every htable
calls, set the pointer in the EXP hbase interface layer with first init
call in the tcb work methods (not the task work methods), then
eventually to the htable JNI layer from getHTableClient()
(sql/exp/ExpHbaseInterface.cpp).
2) Rewrite the way to construct the hbase operator names from one
methord and use it for display both tdb contents and tcb stats.
3) Populate the hbase I/O bytes counter for both read and insert
(sql/executor/HBaseClient_JNI.cpp).
4) Fix the problem that parsing stats variable text string could go
beyond the end of the string (getSubstrInfo() in
sql/executor/ExExeUtilGetStats.cpp).

Change-Id: I62618b57894039bc1ca5bc0f3c9b89efec5cc42e
Merge "Enabling runtime stats for hbase tables and operators"