Revert "Loose coupling"

klacke I was looking at unit test coverage this morning for the jnc folder, its quite low < 30% 

So I decided to run some some integration tests against confd. 

Before getting this far I noticed that pyang generates code that is dependent on concrete types, as a result one of the commits last night thats moves from concrete to interfaces will break the generated code.

Please merge this revert for that single commit. 

Going forward I will only send you updates that have been verified against confd, separately I will look at beefing up the unit tests.

This reverts commit bf64e98049578b1defe953a5e4f0cde8c1156409.