append mail= to prevent pkgadd sending mail

Some installations may not have sendmail installed by default,
resulting in an error such as this when installation completes:

    Thank you for installing Chef!
    exec of "/usr/lib/sendmail" failed: No such file or directory
    mail: ERROR signal 13

    Installation of <chef> was successful.
convert bourne shell to /bin/sh

- AIX, Solaris 9, JunOS, etc need this treatment
more bourne shell fixes and AIX

- i also really, really hate 'then' on its own line
CHEF-3988/OC-7110: SuSE use only maj version

- minor version bumps in SuSE are not ABI changes, similar
  to RHEL
add -f arg and major refactoring
add perl and python download methods
try all install mechanisms until one works
more refactoring
consistent code style
allow downgrading RPMs (parity with dpkg)
freebsd uses "sh" and doesn't have bash by default
misc fixes and passing on sol9-sparc

- was totally broken, passes now on sol9-sparc
- style fixes
- using 'test' instead of '[]'
- fix filename argument, works now
- added some more output detail
add support for BSD's `fetch`

Fetch exists in the base FreeBSD install which makes it perfect for 
getting Chef onto a system so bootstrapping can proceed.