Fix for issue 3006: add password verification when creating new site

When creating new sites using rb-site install on the command-line, no entered
passwords were being verified. If passwords were re-entered incorrectly, it
accepted it, completed all the actions, and on the final step reported that the
passwords were wrong and aborted installation.

Now after passwords are first entered, the confirmation prompt makes sure that
the re-entered password matches the first. In addition, passwords were printed
out to the command line as a default value after the first prompt. This has
been removed.

Bugs closed: 3006

Reviewed at https://reviews.reviewboard.org/r/5424/