For zsh users, to successfully source this environment set up script,
the version of zsh need to be 5.0.6 or above. Users can download the
newest zsh at http://zsh.sourceforge.net/Arc/source.html

, and then
install it manually.

Change-Id: I1877b4030cf8688bce6b2483c302f957f4a5506f
Signed-off-by: d0u9 <[email protected]>