Print adminPass when rebuilding from shell

The 'nova rebuild' command did not print the adminPass returned by the
server. This is because it discards the instance information returned
by the rebuild action and fetchs the information again. This would lose
the adminPass and it would not be printed for the user.

This patch reuses the instance information returned by the rebuild action
which ensures that the adminPass is printed by the shell.

Change-Id: I144bfa298bef529c78ca04042cd37a763537f09e
Closes-bug: 1302696
Merge "Print adminPass when rebuilding from shell"