Implement a --help option

Handle --help nicely.
install-chef-suse: Wait for chef-expander to finish before starting state transitions

Not waiting here can cause the chef searches that crowbar does immediately when
starting a state transition to return incomplete results and cause a broken
setup.
Merge pull request #1824 from dirkmueller/suse/install_chef/usage

Implement a --help option
Merge pull request #1825 from rhafer/master

install-chef-suse: Wait for chef-expander to finish before starting state transitions
Various install script improvements

- Add a --help text
- Check for running as root
- use dialog(1) if available