[AUR-3363] dataframe comparison and support methods

Get DataFrame column Names

Change-Id: I067965b70e60b371c030ec72b7528ebe1e423e6f
[AUR-3363] dataframe comparison and support methods

Get dataframe column names from an R connection and df name

Change-Id: I3ea145b2f184ebb07cdfb3100dbffdbb44aad9dd