Add in backwards compatibility properties for a few DR fields.
Add in backwards compatibility properties for a few DR fields.

Since we totally revamped, we need these hooks so that
downstream consumers can still access the properties.

Signed-off-by: Chris Lalancette <281cd07d7578d97c83271fbbf2faddb83ab3791c@gmail.com>

clalancette/pyiso,clalancette/pycdlib