STORM-365: Add support for Python 3 to the storm command

This patch makes the storm command work with both Python 2 and Python 3.
Remove redundant parentheses.
Fix the output of `storm help`.
Merge branch 'storm-command-python3' of https://github.com/mnogu/incubator-storm into STORM-365

STORM-365: Add support for Python 3 to storm command.
Added STORM-365 to Changelog