Install misc rpm packeges before chef

Be consistent with other *_install methods.
Also remove obvious comments.
Drop support for openSUSE 11

Omnibus installer only supports openSUSE 12.
Ensure rsync is installed on openSUSE

For example the 12.2 AMIs offered by SUSE Studio do not have rsync
installed. (We can not add integration test for them as Omnibus
install.sh does not support 12.2 even though the package for 12.1
works fine.)
Merge branch 'opensuse'
Fix typo in `--omnibus_version` descriptions

[ci-skip]