cc_chef: Update omnibus URL to new Chef TLD.
Handle strings/text type for 'ssh_authorized_keys'

Instead of only expected a list, tuple, or set type
allow for a string type to be passed in, and add log
message that occurs if some other type is used that
can not be correctly processed.
Also allow a dict to be used

When a dict is passed in for 'ssh_authorized_keys' just extract
the keys from the values of the dict (and discard the keys).
Fix the word spacing
Use LOG.warn and handle the None case as well
Be more tolerant of 'ssh_authorized_keys' types

Instead of only expected a list, tuple, or set type
allow for a string type and dict to be passed in for 'ssh_authorized_keys',
and add log message that occurs if some other type is used that
can not be correctly processed.
Update to use a newer and better OMNIBUS_URL

This is minor change which uses the new Chef (company) top
level domain for grabbing the Omnibus installation shell script.