Implement inheritance

[#1]

DTM should allow inheritance of properties:

eg we embed one property on one specific site.

This property inherits from 3 containers:

1) a global web analytics property - managed by a central WA department

2) a global marketing property - managed by a centralmarketing department

3) a local marketing property - managed by a country marketing department

This way every library property stays quite clean and not all logic has to be merged into one property

Additionally not all functionality needs to be adjusted in multiple properties if a change is needed.