Resolve "Patient unit and schedule unit dropdown value when editing incorrect"

The bug came to be because of the fact that the DTO's were not initialized properly. This is now fixed by tweaking them slightly after mapping them. In order to still keep the creation of these DTO's consistent I've created an abstract class which contains a default method to map them. For classes such as Patient and Schedule which need a bit more fine grained tweaking (aka adding unitId to the object) after mapping, this method has been overwritten to include this more finegrained tweaking of the object. Closes #267 (closed)