actions: Used a class instance variable to hold the logger.

Signed-off-by: Joe MacMahon <joe.macmahon@cern.ch>
tests: Updated test for build_mapping.

Signed-off-by: Joe MacMahon <joe.macmahon@cern.ch>
general: Replaced .copy() with deepcopy()

* This fixes a failing test (SchemaTestCase.test_update_mappings)

Signed-off-by: Joe MacMahon <joe.macmahon@cern.ch>