Dsc 83

Hi Shaun,

I've created the initial implementation of creating collection of works from an EAD for dsc-83.  
Could you please review this change?

Thanks,

Shuang
note: flattening the config fields allows overwriting of fields if they have the same name as elsewhere in the config tree/hirearchy. This could produce some interesting bugs further down the track if people don't know not to repeat names in the config.

Maybe put a warning somewhere ? It can't go in the config itself unfortunately as json doesn't allow comments, so maybe in the EADConfiguration class perhaps ?