Add support for FireWorks without MongoDB

In this branch (pull request pending) we have an option in FireWorks without MongoDB (based on mongomock). The data is stored locally in a file. This is a good option for tutorials and testing scenarios.

• The CLI entry points and Jupyter kernel need adaption because with this option there is no launchpad file.

• The functions get_one_node_info and get_all_nodes_info need versions without some pipeline operators that are not yet supported by mongomock.