Disabling tests for now while working on new testing semantics
Removing unnecessary references to MongoDB
No need for this class to be final.
Exhibiting less public methods.

Narrowing down scope to protected/private for internally used methods.
Removing unused methods from public interfaces.
Removing unused reference to internal method.
Extracting ServerStatus class. Removing MongoBridge.

Moving collection initialisation from Core class to the corresponding
model service class.
Removing reference to core class from ActivityWriter.
Changing SystemSetting class to use Persisted interface.