Resolve "Improve generate_question to recognize question type from YAML input file"

In this MR the question type is passed from the yaml directly, therefore the subcommands in the cli parser are removed. Additional changes that enable this are made: the creation of a Factory for Questions, modification of the signatures and references for the xml creation.

Related tests were included, one to test the behavior with and with no type attribute in the yaml file, the second to test the correct class type of each question type.

Closes #26 (closed)