Apply Oslo ModelBase to NeutronBase

Oslo.db has ModelBase which implements most of NeutronBase's code.
Therefore NeutronBase should inherit from ModelBase to keep things DRY.

Fixes bug #1171055

Change-Id: I1a08636a6aa225da8b5d43a0bbcb9b59c057df42
Merge "Apply Oslo ModelBase to NeutronBase"