SharedHeaderBlock: Inline unnecessary format value
Refactor: Reduce repetition with FLOATING_BLOCKS constant
pep8
Add a docstring for _index_steps
Add question header and question to answer block
Move integration tests into their separate folder
Add StepMixin
Add step mixins to XBlocks that can be steps
Add documentation for `<answer>` question element.
Merge pull request #76 from open-craft/assessment-refactoring

Assessment refactoring and question block in answer