Added deprecation support for OSD creation.

This adds the ability for users to use the old and new formats
in their hostname override yaml files. That means they can use
either 'disk' or 'disk:journal' and both will work. Specifyng just
'disk' will cohabitate the journal on the OSD. When you want to
cohabitate the journal on the OSD using the new format, you will
specify 'disk:disk'.