1.4.0 - Documentation + Possibility to call a decorated test function manually.

New features:

• It is now possible to call a test function decorated with @test_steps manually, for example to run it once at the beinning of a test session in order for all imports to be done before actual execution. Fixes #22

Minor:

• steps_harvest_df_utils submodule is now correctly listed in __all__.
• Improved docstrings and documentation page for API reference.

See documentation page for details.