Interpreter tests completed

Signed off by: Alessandro Palmeira <alessandro.palmeira@gmail.com>
Signed off by: Diego Araujo <diegoamc90@gmail.com>
Refactored runner tests, removed runner_mock_helper

Signed off by: Alessandro Palmeira <alessandro.palmeira@gmail.com>
Signed off by: Diego Araujo <diegoamc90@gmail.com>
Refactored aggregator and aggregator tests

Created subtree_elements method on module_result

Signed off by: Diego Araujo <diegoamc90@gmail.com>