Code cleanup in core and hbase module, helpfull enhancements and a bug fix.

Hi Michi,

Sending few patches to your way which
- Kills trailing white-spaces, organize Java imports, correct indentation (no tabs, two spaces)  (code cleanup)
- Add capability to parse human readable number for workload properties, i.e. 1m - 1,000,000; 1K = 1,000  (enhancement)
- Terminate the workload cleanly on SIGTERM (enhancement)
- Make some HBase client parameters (autoFlush, writeBufferSize, writeToWal) configurable (enhancement)
- Use a table pool instead. (enhancement)
- Return 'NoMatchingRecord' if get() returns empty result (bug fix)

Thanks for having a look.
Aditya...