Fhi-aims-step

* Added a first tutorial to the documentation.

* Added the standard properties for energy and gradient drivers so that aims can be
used with the ThermoChemistry, Structure, and Reaction plug-ins.
* Changed defaults to make normal runs easier to set up.

* Fixed issue with the initialization of the fhi-aims.ini file if it did not exist.
* Cleaned up the section for seamm.ini now that it no longer handles the
executable.

* Added ability to write out the input file and not run FHI-aims
* Check if the calculation has been run, and don't rerun FHI-aims
* Switched to new method of executing background jobs that supports containers.

* Plug-in created using the SEAMM plug-in cookiecutter.