Removed docstring for Robocopy step.

All usage information is only in the documentation page now.
Documentation about timezone support in P4 changesource
Release notes for Robocopy and P4 changes.
Fixed P4 source unit tests on Windows

This is because P4 normalizes slashes/backslashes, so we need to set our
expectations right.
Added unit tests for Robocopy step.

Fixed whitespace.