Added commands to Formatters and add TableFormatter.

Each formatter can now accept so called commands.

A command is instance of FormatterCommand and tells the formatter to
print something different than usual data. For example header for
new host, new table with a title or set column names.
storage: Adapt storage scripts to new formatters.
Added -H option to write output in human-friendly units.
storage: Update storage scripts for -H option.

And use LmiCommand.execute() to get the -H value.
Added --no-headings options to suppress table headers.
Added --csv parameter for CSV output.
storage: Use LmiLister for displaying of lmi XXX show output.

So we can get CSV output for free.